Showing 1–50 of 76 results for author: Jin, J

Steady-state phase transition in one-dimensional hybrid contact process

Authors: Lin Shang, Shuai Geng, Xingli Li, Jiasen Jin

Abstract: We investigate the steady-state phase transition in a one-dimensional hybrid contact process. We implement the single-site and cluster mean-field approximations based on the effective fields and present all the possible steady states of the system. We show the existence of the stable absorbing and active phases, and the bistable region in the long-time limit. The saddle-node bifurcation is observe… ▽ More We investigate the steady-state phase transition in a one-dimensional hybrid contact process. We implement the single-site and cluster mean-field approximations based on the effective fields and present all the possible steady states of the system. We show the existence of the stable absorbing and active phases, and the bistable region in the long-time limit. The saddle-node bifurcation is observed at the boundary between the absorbing phase and the bistable region, suggesting a discontinuous phase transition. While the absorbing to active phase transition is continuous. To characterize the nonclassical scaling behavior of the continuous phase transition, we extract the true critical points and exponents by means of the coherent anomaly method. △ Less

Submitted 11 August, 2026; originally announced August 2026.

Comments: 9 pages, 6 figures

Investigating Lipkin-Meshkov-Glick Model and Criticality-Enhanced Metrology in a Coherent Ising Machine

Authors: Shuang-Quan Ma, Jing-Yi-Ran Jin, Chen-Rui Fan, Chuan Wang, Qing Ai

Abstract: Quantum criticality has received extensive attention due to its ability to significantly enhance quantum sensing. But its realization and control in many-body quantum systems remain challenging. We present an effective scheme to simulate the Lipkin-Meshkov-Glick (LMG) model using a coherent Ising machine (CIM) composed of a network of degenerate optical parametric oscillators (DOPO). In our work,… ▽ More Quantum criticality has received extensive attention due to its ability to significantly enhance quantum sensing. But its realization and control in many-body quantum systems remain challenging. We present an effective scheme to simulate the Lipkin-Meshkov-Glick (LMG) model using a coherent Ising machine (CIM) composed of a network of degenerate optical parametric oscillators (DOPO). In our work, the spin variables of the LMG model are mapped onto the phases of DOPO pulses, and the spin-spin interactions are realized by all-to-all couplings among them. Through our investigation of the critical behavior in the antiferromagnetically coupled LMG model in the thermodynamic limit, i.e., $N\rightarrow\infty$, and its application in quantum sensing near the critical point, we verify that the CIM does not only effectively capture the second-order quantum phase transition (QPT) at the critical point but also reconstructs its complete phase diagram under ferromagnetic coupling. Furthermore, we demonstrate how the critical dynamics of this simulation platform can be utilized for quantum-enhanced metrology, achieving a measurement precision that diverges near the critical point of the LMG model. These results highlight the capability of the CIM as a flexible experimental platform for investigating the QPT in the fundamental quantum magnetic models, providing valuable insights into quantum simulation and critical phenomena. △ Less

Submitted 14 March, 2026; originally announced March 2026.

Journal ref: Quantum Sci. Technol. 11 025019 (2026)

Early-stage memory effect on the dephasing charger-mediated quantum battery

Authors: Yu Wang, Jiasen Jin

Abstract: We investigate the performance of the charger-mediated quantum battery modeled by a two-qubit system. One of the qubits acts as the battery and the other acts as the charger which is subjected to a reservoir. We derived the time-local master equation in Lindblad form with a time-dependent dephasing rate. The dephasing rate may be negative in the early-stage of the charging process and thus indicat… ▽ More We investigate the performance of the charger-mediated quantum battery modeled by a two-qubit system. One of the qubits acts as the battery and the other acts as the charger which is subjected to a reservoir. We derived the time-local master equation in Lindblad form with a time-dependent dephasing rate. The dephasing rate may be negative in the early-stage of the charging process and thus indicate the presence of the memory effect. We find that such early-stage memory effect could increase the maximal ergotropy of the battery compared with the one under Markovian approximation with the corresponding asymptotic dephase rate. The enhancement of the performance is explained by means of the non-Markovian quantum jumps. Moreover, a discrete time scheme of the measurement-enhanced quantum battery is proposed in a quantum circuit with global and random local operations. △ Less

Submitted 15 February, 2026; originally announced February 2026.

Comments: 9 pages, 5 figures

Extended Rydberg Lifetimes in a Cryogenic Atom Array

Authors: Junlan Jin, Yue Shi, Youssef Aziz Alaoui, Jingxin Deng, Yukai Lu, Jeff D. Thompson, Waseem S. Bakr

Abstract: We report on the realization of a $^{133}$Cs optical tweezer array in a cryogenic blackbody radiation (BBR) environment. By enclosing the array within a 4K radiation shield, we measure long Rydberg lifetimes, up to $406 (36)\,μ$s for the $55 P_{3/2}$ Rydberg state, a factor of 3.3(3) longer than the room-temperature value. We employ single-photon coupling for coherent manipulation of the ground-Ry… ▽ More We report on the realization of a $^{133}$Cs optical tweezer array in a cryogenic blackbody radiation (BBR) environment. By enclosing the array within a 4K radiation shield, we measure long Rydberg lifetimes, up to $406 (36)\,μ$s for the $55 P_{3/2}$ Rydberg state, a factor of 3.3(3) longer than the room-temperature value. We employ single-photon coupling for coherent manipulation of the ground-Rydberg qubit. We measure a small differential dynamic polarizability of the transition, beneficial for reducing dephasing due to light intensity fluctuations. Our results pave the path for advancing neutral-atom two-qubit gate fidelities as their error budgets become increasingly dominated by $T_1$ relaxation of the ground-Rydberg qubit. △ Less

Submitted 5 February, 2026; originally announced February 2026.

Comments: 6 pages, 4 figures

Journal ref: PRX Quantum 7, 033009 (2026)

Quantum Phase Transitions in Coherent Ising Machines: XY Model for Demonstration

Authors: Jing-Yi-Ran Jin, Shuang-Quan Ma, Qing Ai

Abstract: Quantum phase transitions (QPTs) in coherent Ising machines (CIMs) are studied via a spectral mapping between the one-dimensional XY spin model and a network of degenerate optical parametric oscillators (DOPOs). This exact correspondence reveals that the DOPO network faithfully reproduces the quantum critical behavior of the XY model across its anisotropic, isotropic, and transverse-field Ising re… ▽ More Quantum phase transitions (QPTs) in coherent Ising machines (CIMs) are studied via a spectral mapping between the one-dimensional XY spin model and a network of degenerate optical parametric oscillators (DOPOs). This exact correspondence reveals that the DOPO network faithfully reproduces the quantum critical behavior of the XY model across its anisotropic, isotropic, and transverse-field Ising regimes. The ground-state energy density and its derivatives are analyzed to reveal second-order QPTs characterized by singularities in magnetic susceptibility at critical points. These results show that CIMs do not only serve as powerful platforms for solving combinatorial optimization problems but also provide a versatile optical simulator for studying universal quantum critical phenomena, bridging quantum-spin models and photonic quantum systems. △ Less

Submitted 29 December, 2025; originally announced December 2025.

Comments: 7 pages, 3 figures

Quantum batteries in coherent Ising machine

Authors: Jin-Tian Zhang, Shuang-Quan Ma, Jing-Yi-Ran Jin, Tao Liu, Qing Ai

Abstract: With intensive studies of quantum thermodynamics, quantum batteries (QBs) have been proposed to store and transfer energy via quantum effects. Despite many theoretical models, decoherence remains a severe challenge and practical platforms are still rare. Here, we propose a QB based on the coherent Ising machine, in which the signal field acts as the core energy-storage unit. To clarify the role of… ▽ More With intensive studies of quantum thermodynamics, quantum batteries (QBs) have been proposed to store and transfer energy via quantum effects. Despite many theoretical models, decoherence remains a severe challenge and practical platforms are still rare. Here, we propose a QB based on the coherent Ising machine, in which the signal field acts as the core energy-storage unit. To clarify the role of quantum coherence in resisting dissipation, we decompose the ergotropy, i.e., the maximum extractable work from the QB, into its coherent and incoherent components. We find that the coherent part decays at a rate roughly half that of the incoherent part, exhibiting much stronger robustness against decoherence. More importantly, the coherent ergotropy and the average charging power reach their respective maxima at essentially the same moment, which defines the optimal instant to switch off the pump field. Finally, by coupling the QB to a two-level system as the load, we demonstrate an efficient energy discharge process of the proposed QB. Our work establishes a realistic and immediately-implementable QB architecture on a mature optical platform, laying a foundation for experimental exploration of quantum energy storage. △ Less

Submitted 20 May, 2026; v1 submitted 16 December, 2025; originally announced December 2025.

Comments: 14 pages, 10 figures. Corresponding author: Qing Ai (aiqing@bnu.edu.cn)

Journal ref: Jin-Tian Zhang, Shuang-Quan Ma, Jing-Yi-Ran Jin, Tao Liu, and Qing Ai, Quantum batteries in coherent Ising machine, Phys. Rev. Research 8, 023187 (2026)

Hybrid Quantum Transformer for Language Generation

Authors: Desheng Kong, Xiangshuo Cui, Jiaying Jin, Jing Xu, Donglin Wang

Abstract: Although quantum computing has been increasingly applied to replace classical computation, most existing quantum or hybrid models remain confined to simple tasks, with no successful application to large-scale natural language generation to date. In this work, we present the first hybrid quantum-classical large language model (LLM) for natural language generation, HyQuT, capable of performing coher… ▽ More Although quantum computing has been increasingly applied to replace classical computation, most existing quantum or hybrid models remain confined to simple tasks, with no successful application to large-scale natural language generation to date. In this work, we present the first hybrid quantum-classical large language model (LLM) for natural language generation, HyQuT, capable of performing coherent and context-aware dialogue. The proposed architecture integrates variational quantum circuits (VQCs) into the Transformer framework at both 8M and 150M parameter scales. Experimental results show that a minimal number of qubits (10 qubits with 80 quantum gates) can replace about 10% of the classical parameters in the 150M-parameter model, while achieving comparable convergence stability and generation quality. This study provides an early demonstration of the feasibility of integrating quantum computing to large-scale generative language models. △ Less

Submitted 2 November, 2025; originally announced November 2025.

Steady-state phase transition in one-dimensional quantum contact process

Authors: Lin Shang, Shuai Geng, Xingli Li, Jiasen Jin

Abstract: We investigate the steady-state phases of the one-dimensional quantum contact process model. We present the Liouvillian gap in the thermodynamic limit and uncover the metastability of the system. Exploiting the mean-field approximations with a novel self-consistent condition based on the effective field, we capture the avoid the interference of the metastable state. We show the feature of saddle-n… ▽ More We investigate the steady-state phases of the one-dimensional quantum contact process model. We present the Liouvillian gap in the thermodynamic limit and uncover the metastability of the system. Exploiting the mean-field approximations with a novel self-consistent condition based on the effective field, we capture the avoid the interference of the metastable state. We show the feature of saddle-node bifurcation of the order parameter revealing the discontinuous phase transition of the steady state and extract the transition point for infinite-size system. We show the monotonic decreasing of the steady-state magnetic susceptibility by the linked-cluster expansion, which does not support the divergence of the correlation length at the vicinity of the transition point. The present results may be tested in the quantum simulator of Rydberg atoms. △ Less

Submitted 5 February, 2026; v1 submitted 19 October, 2025; originally announced October 2025.

Comments: Accepted version, 10 pages, 7 figures, including the supplemental material

Journal ref: Phys. Rev. Lett. 136, 050402 (2026)

Cryogenic Magnomechanics for Thermometry Applications

Authors: Y. Huang, P. M. C Rourke, A. Peruzzi, J. Jin, M. Ebrahimi, A. Rashedi, J. P. Davis

Abstract: Cavity magnomechanics combines strong coupling between magnons in a dielectric material and microwave cavity photons with long-lived mechanical resonances. Forming a triple resonance condition, this hybrid quantum system promises many advantages in quantum technologies, yet has never been studied at the cryogenic temperatures required to reveal such quantum properties. We report the observation of… ▽ More Cavity magnomechanics combines strong coupling between magnons in a dielectric material and microwave cavity photons with long-lived mechanical resonances. Forming a triple resonance condition, this hybrid quantum system promises many advantages in quantum technologies, yet has never been studied at the cryogenic temperatures required to reveal such quantum properties. We report the observation of magnomechanics at cryogenic temperatures down to \qty9K. The experiment was conducted using a YIG sphere inside a microwave cavity, where we measured both the thermomechanical motion and the temperature-dependence of the magnon linewidth. △ Less

Submitted 16 March, 2026; v1 submitted 27 March, 2025; originally announced March 2025.

Comments: 5 pages, 5 figures

Journal ref: Appl. Phys. Lett. 23 August 2025; 127 (8): 082405

Non-Markovian Quantum Jump Method for Driven-Dissipative Two-Level Systems

Authors: Huanyuan Zhang, Jiasen Jin

Abstract: We propose a modified non-Markovian quantum jump method to overcome the obstacle of dramatically increased trajectory number in conventional quantum trajectory simulations. In our method the trajectories are classified into the trajectory classes characterized by the number of quantum jumps. We derive the expression of the existence probability of each trajectory (class), which is essential to con… ▽ More We propose a modified non-Markovian quantum jump method to overcome the obstacle of dramatically increased trajectory number in conventional quantum trajectory simulations. In our method the trajectories are classified into the trajectory classes characterized by the number of quantum jumps. We derive the expression of the existence probability of each trajectory (class), which is essential to construct the density matrix of the open quantum system. This modified method costs less computational resources and is more efficient than the conventional quantum trajectory approach. As applications we investigate the dynamics of spin-1/2 systems subject to Lorentzian reservoirs with considering only the no-jump and one-jump trajectories. The revival of coherence and entanglement induced by the memory effect is observed. △ Less

Submitted 15 December, 2025; v1 submitted 2 February, 2025; originally announced February 2025.

Comments: 13 pages, 7 figures

Journal ref: Phys. Rev. A 112, 062214 (2025)

Non-Hermitian Hamiltonian Approach for Two-Dimensional Coherent Spectra of Driven Systems

Authors: Hao-Yue Zhang, Yi-Xuan Yao, Bin-Yao Huang, Jing-Yi-Ran Jin, Qing Ai

Abstract: Two-dimensional coherent spectroscopy (2DCS) offers significant advantages in terms of high temporal and frequency resolutions and signal-to-noise ratio. Until now, the response-function (RF) formalism has been the prevalent theoretical description. In this study, we compare the non-Hermitian Hamiltonian (NHH) method with the RF formalism in a three-level system with a constant control field. We o… ▽ More Two-dimensional coherent spectroscopy (2DCS) offers significant advantages in terms of high temporal and frequency resolutions and signal-to-noise ratio. Until now, the response-function (RF) formalism has been the prevalent theoretical description. In this study, we compare the non-Hermitian Hamiltonian (NHH) method with the RF formalism in a three-level system with a constant control field. We obtain the signals from both approaches and compare their population dynamics and 2DCS. We propose the quasi-Green functions for the NHH method, which allows all dominant Liouville paths to be inferred. We further simulate the 2DCS of Rh(CO)$_2$C$_5$H$_7$O$_2$ (RDC) dissolved in hexane with the NHH method, which is in good agreement with the previous experiments. Although the NHH method overestimates relaxations, it provides all important paths by analytical solutions, which are different from the four paths used in the RF formalism. Our results demonstrate that the NHH method is more suitable than the RF formalism for investigating the systems including relaxation and control fields via the 2DCS. △ Less

Submitted 13 April, 2025; v1 submitted 23 October, 2024; originally announced October 2024.

Journal ref: J. Chem. Theory Comput. 21, 4067-4079 (2025)

Exploring the role of criticality in the quantum Otto cycle fueled by the anisotropic quantum Rabi-Stark model

Authors: He-Guang Xu, Jiasen Jin, Norton G. de Almeida, G. D. de Moraes Neto

Abstract: Quantum heat machines, encompassing heat engines, refrigerators, heaters, and accelerators, represent the forefront of quantum thermodynamics, offering a novel paradigm for converting heat energy into useful mechanical work. Leveraging quantum mechanical principles, these machines promise superior efficiency and performance compared to classical counterparts, with potential applications in renewab… ▽ More Quantum heat machines, encompassing heat engines, refrigerators, heaters, and accelerators, represent the forefront of quantum thermodynamics, offering a novel paradigm for converting heat energy into useful mechanical work. Leveraging quantum mechanical principles, these machines promise superior efficiency and performance compared to classical counterparts, with potential applications in renewable energy and quantum computing. This paper investigates a quantum Otto engine operating in both ideal and finite-time scenarios, employing a two-level system interacting with a harmonic oscillator within the framework of the anisotropic quantum Rabi-Stark model (AQRSM) as the working medium. This model is notable for exhibiting both first-order and continuous quantum phase transitions. By focusing on quantum heat engines, our study reveals that these phase transitions critically modulate the efficiency and power of AQRSM-based engines, outperforming quantum engines fueled by working medium with harmonic spectrum. Additionally, we explore the impacts of quantum friction and conduct limit cycle analysis in finite-time operations, providing insights into optimizing quantum heat engines for practical implementation. △ Less

Submitted 12 July, 2024; originally announced July 2024.

Majorana qubit readout by a point-contact detector under finite bias voltages

Authors: Huizi Xie, Sirui Yu, Hong Mao, Jinshuang Jin

Abstract: In this work we revisit the problem of a Majorana box qubit (MBQ) readout by a point-contact (PC) detector. The logic states of the MBQ are associated with the combined fermion parities of the MBQ and its tunnel-coupled quantum dot, which is measured by a PC detector. Beyond the existing studies on limiting bias voltage regimes, we analyze the steady-state current and the current power spectrum ac… ▽ More In this work we revisit the problem of a Majorana box qubit (MBQ) readout by a point-contact (PC) detector. The logic states of the MBQ are associated with the combined fermion parities of the MBQ and its tunnel-coupled quantum dot, which is measured by a PC detector. Beyond the existing studies on limiting bias voltage regimes, we analyze the steady-state current and the current power spectrum across all bias voltages. Our results indicate that the MBQ readout via the parity-dependent detector current is effective only at low bias voltage regime and requires the dot energy level to be off-resonance with the Majorana qubit. In contrast, the current power spectrum allows MBQ readout through the parity-dependent Rabi oscillation peak signals for arbitrary bias voltages, without restrictions on the dot energy level. Particularly, with focus on the MBQ measurement visibility, we analyze the peak-to-pedestal ratio for each characteristic peak (associated with each logic state of the qubit) and the signal-to-noise ratio of the two peaks. By examining these two metrics, we identify the optimal bias voltage window for the PC detector at low temperature limit. △ Less

Submitted 10 February, 2025; v1 submitted 16 June, 2024; originally announced June 2024.

Comments: 7 pages, 4 figures

Journal ref: PhysRevB.111.075412 (2025)

Anomalously reduced homogeneous broadening of two-dimensional electronic spectroscopy at high temperature by detailed balance

Authors: Ru-Qiong Deng, Cheng-Ge Liu, Yi-Xuan Yao, Jing-Yi-Ran Jin, Hao-Yue Zhang, Yin Song, Qing Ai

Abstract: Dissipation and decoherence of quantum systems in thermal environments is important to various spectroscopies. It is generally believed that dissipation can broaden the line shape of spectroscopies, and thus stronger system-bath interaction can result in more significant homogeneous broadening of two-dimensional electronic spectroscopy (2DES). Here we show that the case can be the opposite in the… ▽ More Dissipation and decoherence of quantum systems in thermal environments is important to various spectroscopies. It is generally believed that dissipation can broaden the line shape of spectroscopies, and thus stronger system-bath interaction can result in more significant homogeneous broadening of two-dimensional electronic spectroscopy (2DES). Here we show that the case can be the opposite in the regime of electromagnetically induced transparency (EIT). We predict that assisted by EIT, the homogeneous broadening of the 2DES at a higher temperature can be significantly reduced due to the detailed balance. This anomalous effect is due to the long-lasting off-diagonal peaks in 2DES. △ Less

Submitted 3 May, 2024; originally announced May 2024.

Comments: 10 pages, 6 figures

Journal ref: Phys. Rev. A 109, 052801 (2024)

Witnessing non-Markovianity with Gaussian quantum steering in collision model

Authors: Yan Li, Xingli Li, Jiasen Jin

Abstract: The nonincreasing feature of temporal quantum steering under a completely positive trace-preserving (CPTP) map, as proposed by Chen, et al. in Phys. Rev. Lett. 116, 020503 (2016), has been considered as a practical measure of non-Markovianity. In this paper, we utilize an all-optical scheme to simulate a non-Markovian collision model and to examine how Gaussian steering can be used as a tool for q… ▽ More The nonincreasing feature of temporal quantum steering under a completely positive trace-preserving (CPTP) map, as proposed by Chen, et al. in Phys. Rev. Lett. 116, 020503 (2016), has been considered as a practical measure of non-Markovianity. In this paper, we utilize an all-optical scheme to simulate a non-Markovian collision model and to examine how Gaussian steering can be used as a tool for quantifying the non-Markovianity of a structured continuous variable (CV) Gaussian channel. By modifying the reflectivity of the beam splitters (BSs), we are able to tune the degree of non-Markovianity of the channel. After analyzing the non-Markovian degree of the dissipative channel within two steering scenarios, we discovered that the Gaussian steering-based non-Markovian measure depends the specific scenario because of the asymmetry of Gaussian steering. We also compared the Gaussian steering based non-Markovianity to the one based on the violation of the divisibility of CPTP map. △ Less

Submitted 1 May, 2024; v1 submitted 1 February, 2024; originally announced February 2024.

Comments: 14 pages, 7 figures, accepted version

Journal ref: Phys. Rev. A 109, 052201 (2024)

Observing Quantum Coherent Oscillations in a Three-Level Atoms via Electromagnetically Induced Transparency by Two-Dimensional Spectroscopy

Authors: Jing-Yi-Ran Jin, Hao-Yue Zhang, Yi-Xuan Yao, Rong-Hang Chen, Qing Ai

Abstract: Two-dimensional electronic spectroscopy (2DES) has high spectral resolution and is a useful tool for studying atom dynamics. In this paper, we show a smallest unit of electromagnetically induced transparency (EIT) for 2DES, that is, a three-level system. It is found that the original main peak is split into four small ones due to the introduction of the EIT. It suggests that the homogeneous broade… ▽ More Two-dimensional electronic spectroscopy (2DES) has high spectral resolution and is a useful tool for studying atom dynamics. In this paper, we show a smallest unit of electromagnetically induced transparency (EIT) for 2DES, that is, a three-level system. It is found that the original main peak is split into four small ones due to the introduction of the EIT. It suggests that the homogeneous broadening of 2DES can be effectively reduced by the EIT. Moreover, in sharp contrast to a constant height, the height of the peaks will manifest a damped oscillation with respect to the population time. It seems that the quantum-beat phenomenon appears. These findings may help us obtain more information about the dynamics of excited states. △ Less

Submitted 4 January, 2025; v1 submitted 14 January, 2024; originally announced January 2024.

Comments: 8 pages, 10 figures

Journal ref: J. Chem. Phys. 162, 014112 (2025)

Persisting quantum effects in the anisotropic Rabi model at thermal equilibrium

Authors: He-Guang Xu, V. Montenegro, Gao Xianlong, Jiasen Jin, G. D. de Moraes Neto

Abstract: Quantum correlations and nonclassical states are at the heart of emerging quantum technologies. Efforts to produce long-lived states of such quantum resources are a subject of tireless pursuit. Among several platforms useful for quantum technology, the mature quantum system of light-matter interactions offers unprecedented advantages due to current on-chip nanofabrication, efficient quantum contro… ▽ More Quantum correlations and nonclassical states are at the heart of emerging quantum technologies. Efforts to produce long-lived states of such quantum resources are a subject of tireless pursuit. Among several platforms useful for quantum technology, the mature quantum system of light-matter interactions offers unprecedented advantages due to current on-chip nanofabrication, efficient quantum control of its constituents, and its wide range of operational regimes. Recently, a continuous transition between the Jaynes-Cummings model and the Rabi model has been proposed by exploiting anisotropies in their light-matter interactions, known as the anisotropic quantum Rabi model. In this work, we study the long-lived quantum correlations and nonclassical states generated in the anisotropic Rabi model and how these indeed persist even at thermal equilibrium. To achieve this, we thoroughly analyze several quantumness quantifiers, where the long-lived quantum state is obtained from a dressed master equation that is valid for all coupling regimes and with the steady state ensured to be the canonical Gibbs state. Furthermore, we demonstrate a stark distinction between virtual excitations produced beyond the strong coupling regime and the quantumness quantifiers once the light-matter interaction has been switched off. This raises the key question about the nature of the equilibrium quantum features generated in the anisotropic quantum Rabi model and paves the way for future experimental investigations, without the need for challenging ground-state cooling. △ Less

Submitted 5 September, 2023; originally announced September 2023.

On-chip indistinguishable photons using III-V nanowire/SiN hybrid integration

Authors: Edith Yeung, David B. Northeast, Jeongwan Jin, Patrick Laferrière, Marek Korkusinski, Philip J. Poole, Robin L. Williams, Dan Dalacu

Abstract: We demonstrate on-chip generation of indistinguishable photons based on a nanowire quantum dot. From a growth substrate containing arrays of positioned-controlled single dot nanowires, we select a single nanowire which is placed on a SiN waveguide fabricated on a Si-based chip. Coupling of the quantum dot emission to the SiN waveguide is via the evanescent mode in the tapered nanowire. Post-select… ▽ More We demonstrate on-chip generation of indistinguishable photons based on a nanowire quantum dot. From a growth substrate containing arrays of positioned-controlled single dot nanowires, we select a single nanowire which is placed on a SiN waveguide fabricated on a Si-based chip. Coupling of the quantum dot emission to the SiN waveguide is via the evanescent mode in the tapered nanowire. Post-selected two-photon interference visibilities using continuous wave excitation above-band and into a p-shell of the dot were 100%, consistent with a single photon source having negligible multi-photon emission probability. Visibilities over the entire photon wavepacket, measured using pulsed excitation, were reduced by a factor of 5 when exciting quasi-resonantly and by a factor of 10 for above-band excitation. The role of excitation timing jitter, spectral diffusion and pure dephasing in limiting visibilities over the temporal extent of the photon is investigated using additional measurements of the coherence and linewidth of the emitted photons. △ Less

Submitted 20 August, 2023; originally announced August 2023.

Universal quantum Otto heat machine based on the Dicke model

Authors: He-Guang Xu, Jiasen Jin, G. D. M. Neto, Norton G. de Almeida

Abstract: In this paper we study a quantum Otto thermal machine where the working substance is composed of N identical qubits coupled to a single mode of a bosonic field, where the atoms and the field interact with a reservoir, as described by the so-called open Dicke model. By controlling the relevant and experimentally accessible parameters of the model we show that it is possible to build a universal qua… ▽ More In this paper we study a quantum Otto thermal machine where the working substance is composed of N identical qubits coupled to a single mode of a bosonic field, where the atoms and the field interact with a reservoir, as described by the so-called open Dicke model. By controlling the relevant and experimentally accessible parameters of the model we show that it is possible to build a universal quantum heat machine (UQHM) that can function as an engine, refrigerator, heater or accelerator. The heat and work exchanges are computed taking into account the growth of the number N of atoms as well as the coupling regimes characteristic of the Dicke model for several ratios of temperatures of the two thermal reservoirs. The analysis of quantum features such as entanglement and second-order correlation shows that these quantum resources do not affect either the efficiency or the performance of the UQHM based on the open Dicke Model. In addition, we show that the improvement in both efficiency and coefficient of performance of our UQHM occurs for regions around the critical value of the phase transition parameter of the model. △ Less

Submitted 12 August, 2023; originally announced August 2023.

Crossover from the discontinuous to continuous phase transitions in dissipative spin system with collective decay

Authors: Linyu Song, Jiasen Jin

Abstract: We investigate the steady-state phase transitions in an all-to-all transverse-field Ising model subjected to an environment. The considered model is composed of two ingredient Hamiltonians. The orientation of the external field, which is perpendicular to the spin interaction, can be tuned to be along either $x$ direction or $z$ direction in each ingredient Hamiltonian while the dissipations always… ▽ More We investigate the steady-state phase transitions in an all-to-all transverse-field Ising model subjected to an environment. The considered model is composed of two ingredient Hamiltonians. The orientation of the external field, which is perpendicular to the spin interaction, can be tuned to be along either $x$ direction or $z$ direction in each ingredient Hamiltonian while the dissipations always tend to flip the spins down to the $z$ direction. By means of mean-field approximation, we find that the quasi continuous steady-state phase transition is presented as a consequence of the merging of two branches of steady-state solutions. The emergence of bistability is confirmed by analyzing the steady-state behaviors of a set of finite-size systems which is also revealed by the Liouvillian spectrum. △ Less

Submitted 9 August, 2023; v1 submitted 19 April, 2023; originally announced April 2023.

Comments: 9 pages, 6 figures

Journal ref: Phys. Rev. B 108, 054302 (2023)

High threshold codes for neutral atom qubits with biased erasure errors

Authors: Kaavya Sahay, Junlan Jin, Jahan Claes, Jeff D. Thompson, Shruti Puri

Abstract: The requirements for fault-tolerant quantum error correction can be simplified by leveraging structure in the noise of the underlying hardware. In this work, we identify a new type of structured noise motivated by neutral atom qubits, biased erasure errors, which arises when qubit errors are dominated by detectable leakage from only one of the computational states of the qubit. We study the perfor… ▽ More The requirements for fault-tolerant quantum error correction can be simplified by leveraging structure in the noise of the underlying hardware. In this work, we identify a new type of structured noise motivated by neutral atom qubits, biased erasure errors, which arises when qubit errors are dominated by detectable leakage from only one of the computational states of the qubit. We study the performance of this model using gate-level simulations of the XZZX surface code. Using the predicted erasure fraction and bias of metastable $^{171}$Yb qubits, we find a threshold of 8.2% for two-qubit gate errors, which is 1.9 times higher than the threshold for unbiased erasures, and 7.5 times higher than the threshold for depolarizing errors. Surprisingly, the improved threshold is achieved without bias-preserving controlled-not gates, and instead results from the lower noise entropy in this model. We also introduce an XZZX cluster state construction for measurement-based error correction, hybrid-fusion, that is optimized for this noise model. By combining fusion operations and deterministic entangling gates, this construction preserves the intrinsic symmetry of the XZZX code, leading to a higher threshold of 10.3% and enabling the use of rectangular codes with fewer qubits. We discuss a potential physical implementation using a single plane of atoms and moveable tweezers. △ Less

Submitted 17 October, 2023; v1 submitted 6 February, 2023; originally announced February 2023.

Comments: 12+8 pages, 4+4 figures, comments welcome; v2 - extended discussion on resource overhead in supplement, references added

Journal ref: Phys. Rev. X 13, 041013 (2023)

Quantum non-stationary phenomena of spin systems in collision models

Authors: Yan Li, Xingli Li, Jiasen Jin

Abstract: We investigate the non-stationary phenomenon in a tripartite spin-1/2 system in the collision model (CM) framework. After introducing the dissipation through the system-environment collision for both Markovian and non-Markovian cases, we find the emergence of long-time oscillation in the dynamics of the system and the synchronization among subsystems. We connect the CM description and the quantum… ▽ More We investigate the non-stationary phenomenon in a tripartite spin-1/2 system in the collision model (CM) framework. After introducing the dissipation through the system-environment collision for both Markovian and non-Markovian cases, we find the emergence of long-time oscillation in the dynamics of the system and the synchronization among subsystems. We connect the CM description and the quantum master equation in the continuous time limit and explain the existence of the stable oscillation by means of Liouvillian spectrum analysis. The time-dependence of the thermal property and the correlations are investigated, in particular we discuss the possibility of violation of the Landauer's principle in non-Markovian dynamics. In addition, we find that the imperfection of collective dissipation can be compensated by the randomness of the interaction sequence in our CM. △ Less

Submitted 8 April, 2023; v1 submitted 31 October, 2022; originally announced October 2022.

Comments: 13 pages, 8 figures, accepted version

Journal ref: Phys. Rev. A 107, 042205 (2023)

Continuous phase transition induced by non-Hermiticity in the quantum contact process model

Authors: Wen-Bin He, Jiasen Jin, Fernando Iemini, Hai-Qing Lin

Abstract: Non-Hermitian quantum system recently have attracted a lots of attentions theoretically and experimentally. However, the results based on the single-particle picture may not apply to understand the property of non-Hermitian many-body system. How the property of quantum many-body system especially the phase transition will be affected by the non-hermiticity remains unclear. Here we study non-Hermit… ▽ More Non-Hermitian quantum system recently have attracted a lots of attentions theoretically and experimentally. However, the results based on the single-particle picture may not apply to understand the property of non-Hermitian many-body system. How the property of quantum many-body system especially the phase transition will be affected by the non-hermiticity remains unclear. Here we study non-Hermitian quantum contact process (QCP) model, whose effective Hamiltonian is derived from Lindbladian master equation. We show that there is a continuous phase transition induced by the non-hermiticity in QCP. We also determine the critical exponents $β$ of order parameter, $γ$ of susceptibility and study the correlation and entanglement near phase transition. We observe that the order parameter and susceptibility display infinitely singularity even for finite size system, since non-hermiticity endow many-body system with different singular behaviour from classical phase transition. Moreover our results show that the phase transition have no counterpart in Hermitian case and belongs to completely different universality class. △ Less

Submitted 20 October, 2023; v1 submitted 21 September, 2022; originally announced September 2022.

Journal ref: J. Phys. A: Math. Theor. 56 455001 (2023)

Synchronization of persistent oscillations in spin systems with non-local dissipations

Authors: Xingli Li, Yan Li, Jiasen Jin

Abstract: We explore the synchronization phenomenon in the quantum few-body system of spins with the non-local dissipation. Without the external driving, we find that the system can exhibit stable oscillatory behaviors in the long-time dynamics accompanied by the appearance of the purely imaginary eigenvalues of the Liouvillian. Moreover, the oscillations of the next-nearest-neighboring spins are completely… ▽ More We explore the synchronization phenomenon in the quantum few-body system of spins with the non-local dissipation. Without the external driving, we find that the system can exhibit stable oscillatory behaviors in the long-time dynamics accompanied by the appearance of the purely imaginary eigenvalues of the Liouvillian. Moreover, the oscillations of the next-nearest-neighboring spins are completely synchronized revealed by the quantum trajectory analysis within the stochastic Schrödinger equation. The possibility of the appearance of the long-time oscillations in infinite-size lattice by means of cluster mean-field approximation is also discussed. △ Less

Submitted 30 March, 2023; v1 submitted 14 July, 2022; originally announced July 2022.

Comments: 12 pages, 8 figures, accepted version

Journal ref: Phys. Rev. A 107, 032219 (2023)

Parameter estimation with the steady states of non-Hermitian spin chains

Authors: Huiqin Zhang, Jiasen Jin

Abstract: We propose a scheme for parameter estimation with the steady states of non-Hermitian spin chains. The parameters to be estimated are encoded in the system via the external magnetic field that imposed on the first site of the chain. We obtain the analytical spectrum for the spin chain of two sites. We find that the quantum Fisher information (QFI) about the amplitude of the imposing field diverges… ▽ More We propose a scheme for parameter estimation with the steady states of non-Hermitian spin chains. The parameters to be estimated are encoded in the system via the external magnetic field that imposed on the first site of the chain. We obtain the analytical spectrum for the spin chain of two sites. We find that the quantum Fisher information (QFI) about the amplitude of the imposing field diverges while the QFI about the azimuthal angle reaches to the maximum at exceptional points. Moreover, the QFI is enhanced as the system size increasing and saturates for sufficiently long spin chain because only short-range correlations are induced by the imposing field. △ Less

Submitted 5 June, 2022; originally announced June 2022.

Comments: 6 pages, 5 figures, accepted version

Journal ref: Physica A 599, 127460 (2022)

Dissipation induced information scrambling in a collision model

Authors: Yan Li, Xingli Li, Jiasen Jin

Abstract: In this paper, we present a collision model to stroboscopically simulate the dynamics of information in dissipative systems. In particular, an all-optical scheme is proposed to investigate the information scrambling of bosonic systems with Gaussian environmental states. By varying the states of environments, we find that in the presence of dissipation the transient tripartite mutual information of… ▽ More In this paper, we present a collision model to stroboscopically simulate the dynamics of information in dissipative systems. In particular, an all-optical scheme is proposed to investigate the information scrambling of bosonic systems with Gaussian environmental states. By varying the states of environments, we find that in the presence of dissipation the transient tripartite mutual information of system modes may show negative value signaling the appearance of information scrambling. We also find that dynamical indivisibility based non-Markovianity play dual roles in affecting the dynamics of information. △ Less

Submitted 13 March, 2022; v1 submitted 27 January, 2022; originally announced January 2022.

Comments: 11 pages, 6 figures, accepted version

Journal ref: Entropy 24, 345 (2022)

Steady-state susceptibility in continuous phase transitions of dissipative systems

Authors: Xingli Li, Yan Li, Jiasen Jin

Abstract: In this work, we explore the critical behaviors of fidelity susceptibility and trace distance susceptibility associated to the steady states of dissipative systems at continuous phase transitions. We investigate on two typical models, one is the dissipative spin-1/2 XYZ model on two-dimensional square lattice and the other is a driven-dissipative Kerr oscillator. We find that the susceptibilities… ▽ More In this work, we explore the critical behaviors of fidelity susceptibility and trace distance susceptibility associated to the steady states of dissipative systems at continuous phase transitions. We investigate on two typical models, one is the dissipative spin-1/2 XYZ model on two-dimensional square lattice and the other is a driven-dissipative Kerr oscillator. We find that the susceptibilities of fidelity and trace distance exhabit singular behaviors near the critical points of phase transitions in both models. The critical points, in thermodynamic limit, extracted from the scalings of the critical controlling parameters to the system size or nonlinearity agree well with the existed results. △ Less

Submitted 28 May, 2022; v1 submitted 12 January, 2022; originally announced January 2022.

Comments: 9 pages, 9 figures, accepted version

Journal ref: Phys. Rev. A 105, 052226 (2022)

Microwave Amplification in a PT -symmetric-like Cavity Magnomechanical System

Authors: Hua Jin, Zhi-Bo Yang, Jing-Wen Jin, Jian-Yu Liu, Hong-Yu Liu, Rong-Can Yang

Abstract: We propose a scheme that can generate tunable magnomechanically induced amplification in a double-cavity parity-time-(PT -) symmetric-like magnomechanical system under a strong control and weak probe field. The system consists of a ferromagnetic-material yttrium iron garnet (YIG) sphere placed in a passive microwave cavity which is connected with another active cavity. We reveal that ideally induc… ▽ More We propose a scheme that can generate tunable magnomechanically induced amplification in a double-cavity parity-time-(PT -) symmetric-like magnomechanical system under a strong control and weak probe field. The system consists of a ferromagnetic-material yttrium iron garnet (YIG) sphere placed in a passive microwave cavity which is connected with another active cavity. We reveal that ideally induced amplification of the microwave probe signal may reach the maximum value 1000000 when cavity-cavity, cavity-magnon and magnomechanical coupling strengths are nonzero simultaneously. The phenomenon might have potential applications in the field of quantum information processing and quantum optical devices. Besides, we also find the phenomena of slow-light propagation. In this case, group speed delay of the light can achieve 0.000035s, which can enhance some nonlinear effect. Moreover, due to the relatively flat dispersion curve, the proposal may be applied to sensitive optical switches, which plays an important role in storing photons and quantum optical chips. △ Less

Submitted 3 December, 2021; originally announced December 2021.

Comments: 6 pages,6 figures

MSC Class: 81-10 ACM Class: J.2

Steady-state phases of dissipative spin-1/2 XYZ model with frustrated interaction

Authors: Xingli Li, Yan Li, Jiasen Jin

Abstract: We investigate the steady-state phases of the dissipative spin-1/2 $J_1$-$J_2$ XYZ model on a two-dimensional square lattice. We show the next-nearest-neighboring interaction plays a crucial role in determining the steady-state properties. By means of the Gutzwiller mean-field factorization, we find the emergence of antiferromag-netic steady-state phases. The existence of such antiferromagnetic st… ▽ More We investigate the steady-state phases of the dissipative spin-1/2 $J_1$-$J_2$ XYZ model on a two-dimensional square lattice. We show the next-nearest-neighboring interaction plays a crucial role in determining the steady-state properties. By means of the Gutzwiller mean-field factorization, we find the emergence of antiferromag-netic steady-state phases. The existence of such antiferromagnetic steady-state phases in thermodynamic limit is confirmed by the cluster mean-field analysis. Moreover, we find the evidence of the limit cycle phase through the largest quantum Lyapunov exponent in small cluster, and check the stability of the oscillation by calculating the averaged oscillation amplitude up to $4\times4$ cluster mean-field approximation. △ Less

Submitted 20 October, 2021; v1 submitted 22 July, 2021; originally announced July 2021.

Comments: 10 pages, 8 figures, accepted version

Journal ref: Phys. Rev. B 104, 155130 (2021)

Determination of the critical exponents in dissipative phase transitions: Coherent anomaly approach

Authors: Jiasen Jin, Wen-Bin He, Fernando Iemini, Diego Ferreira, Ying-Dan Wang, Stefano Chesi, Rosario Fazio

Abstract: We propose a generalization of the coherent anomaly method to extract the critical exponents of a phase transition occurring in the steady-state of an open quantum many-body system. The method, originally developed by Suzuki [J. Phys. Soc. Jpn. {\bf 55}, 4205 (1986)] for equilibrium systems, is based on the scaling properties of the singularity in the response functions determined through cluster… ▽ More We propose a generalization of the coherent anomaly method to extract the critical exponents of a phase transition occurring in the steady-state of an open quantum many-body system. The method, originally developed by Suzuki [J. Phys. Soc. Jpn. {\bf 55}, 4205 (1986)] for equilibrium systems, is based on the scaling properties of the singularity in the response functions determined through cluster mean-field calculations. We apply this method to the dissipative transverse-field Ising model and the dissipative XYZ model in two dimensions obtaining convergent results already with small clusters. △ Less

Submitted 1 December, 2021; v1 submitted 12 March, 2021; originally announced March 2021.

Comments: Accepted version, 9 pages, 7 figures

Journal ref: Phys. Rev. B 104, 214301 (2021)

Nonuniform phases in the geometrically frustrated dissipative XYZ model

Authors: Xingli Li, Jiasen Jin

Abstract: We investigate the steady-state phase diagram of the dissipative spin-1/2 XYZ model on a two-dimensional triangular lattice, in which each site is coupled to a local environment. By means of cluster mean-field approximation, we find that the steady-state phases of the system are rather rich, in particular there exist various types of nonuniform antiferromagnetic phases due to the geometrical frust… ▽ More We investigate the steady-state phase diagram of the dissipative spin-1/2 XYZ model on a two-dimensional triangular lattice, in which each site is coupled to a local environment. By means of cluster mean-field approximation, we find that the steady-state phases of the system are rather rich, in particular there exist various types of nonuniform antiferromagnetic phases due to the geometrical frustration. As the short-range correlations included in the analysis, the numerical results show that the oscillatory phase disappears while the triantiferromagnetic and biantiferromagnetic phases remain to exist in the thermodynamic limit. Moreover, the existence of the spin-density-wave phase, which is missed by the single-site mean-field analysis, is also revealed by the spin-structure factor. △ Less

Submitted 19 January, 2021; v1 submitted 29 November, 2020; originally announced November 2020.

Comments: 8 pages, 7 figures

Journal ref: Phys. Rev. B 103, 035127 (2021)

Hong-Ou-Mandel interference of unconventional temporal laser modes

Authors: Sascha Agne, Jeongwan Jin, Katanya B. Kuntz, Filippo M. Miatto, Jean-Philippe Bourgoin, Thomas Jennewein

Abstract: The Hong-Ou-Mandel (HOM) effect ranks among the most notable quantum interference phenomena, and is central to many applications in quantum technologies. The fundamental effect appears when two independent and indistinguishable photons are superimposed on a beam splitter, which achieves a complete suppression of coincidences between the two output ports. Much less studied, however, is when the fie… ▽ More The Hong-Ou-Mandel (HOM) effect ranks among the most notable quantum interference phenomena, and is central to many applications in quantum technologies. The fundamental effect appears when two independent and indistinguishable photons are superimposed on a beam splitter, which achieves a complete suppression of coincidences between the two output ports. Much less studied, however, is when the fields share coherence (continuous-wave lasers) or mode envelope properties (pulsed lasers). In this case, we expect the existence of two distinct and concurrent HOM interference regimes: the traditional HOM dip on the coherence length time scale, and a structured HOM interference pattern on the pulse length scale. We develop a theoretical framework that describes HOM interference for laser fields having arbitrary temporal waveforms and only partial overlap in time. We observe structured HOM interference from a continuous-wave laser via fast polarization modulation and time-resolved single photon detection fast enough to resolve these structured HOM dips. △ Less

Submitted 17 June, 2020; v1 submitted 23 April, 2020; originally announced April 2020.

Comments: 11 pages, 4 figures

Journal ref: Optics Express, 28, 20943 (2020)

Information scrambling in a collision model

Authors: Yan Li, Xingli Li, Jiasen Jin

Abstract: The information scrambling in many-body systems is closely related to quantum chaotic dynamics, complexity, and gravity. Here we propose a collision model to simulate the information dynamics in an all-optical system. In our model the information is initially localized in the memory and evolves under the combined actions of many-body interactions and dissipation. We find that the information is sc… ▽ More The information scrambling in many-body systems is closely related to quantum chaotic dynamics, complexity, and gravity. Here we propose a collision model to simulate the information dynamics in an all-optical system. In our model the information is initially localized in the memory and evolves under the combined actions of many-body interactions and dissipation. We find that the information is scrambled if the memory and environmental particles are alternatively squeezed along two directions which are perpendicular to each other. Moreover, the disorder and imperfection of the interaction strength tend to prevent the information flow away to the environment and lead to the information scrambling in the memory. We analyze the spatial distributions of the correlations in the memory. Our proposal is possible to realize with current experimental techniques. △ Less

Submitted 21 April, 2020; v1 submitted 12 February, 2020; originally announced February 2020.

Comments: 9 pages, 6 figures, accepted version

Journal ref: Phys. Rev. A 101, 042324 (2020)

Experimental demonstration of one-shot coherence distillation: High-dimensional state conversions

Authors: Shao-Jie Xiong, Zhe Sun, Xiaofeng Li, Qi-Ping Su, Zhengjun Xi, Li Yu, Jin-Shuang Jin, Jin-Ming Liu, Franco Nori, Chui-Ping Yang

Abstract: We experimentally investigate problems of one-shot coherence distillation [Regula, Fang, Wang, and Adesso, Phys. Rev. Lett. 121, 010401 (2018)]. Based on a set of optical devices, we design a type of strictly incoherent operation (SIO), which is applicable in high-dimensional cases and can be applied to accomplish the transformations from higher-dimensional states to lower-dimensional states. Furt… ▽ More We experimentally investigate problems of one-shot coherence distillation [Regula, Fang, Wang, and Adesso, Phys. Rev. Lett. 121, 010401 (2018)]. Based on a set of optical devices, we design a type of strictly incoherent operation (SIO), which is applicable in high-dimensional cases and can be applied to accomplish the transformations from higher-dimensional states to lower-dimensional states. Furthermore, a relatively complete process of the one-shot coherence distillation is experimentally demonstrated for three- and four-dimensional input states. Experimental data reveal an interesting result: higher coherence distillation rates (but defective) can be reached by tolerating a larger error. Our finding paves a fresh way in the experimental investigation of quantum coherence conversions through various incoherent operations. △ Less

Submitted 4 December, 2019; v1 submitted 19 November, 2019; originally announced November 2019.

Comments: 9 pages, 4 figures

Journal ref: OPTICA vol.8, issue 7, pp.1003-1008(2021)

A framework for quantum homomorphic encryption with experimental demonstration

Authors: Yu Zhang, Li Yu, Qi-Ping Su, Zhe Sun, Fuqun Wang, Xiao-Qiang Xu, Qingjun Xu, Jin-Shuang Jin, Kefei Chen, Chui-Ping Yang

Abstract: Quantum homomorphic encryption (QHE) is an encryption method that allows quantum computation to be performed on one party's private data with the program provided by another party, without revealing much information about the data nor the program to the opposite party. We propose a framework for (interactive) QHE based on the universal circuit approach. It contains a subprocedure of calculating a… ▽ More Quantum homomorphic encryption (QHE) is an encryption method that allows quantum computation to be performed on one party's private data with the program provided by another party, without revealing much information about the data nor the program to the opposite party. We propose a framework for (interactive) QHE based on the universal circuit approach. It contains a subprocedure of calculating a classical linear polynomial, which can be implemented with quantum or classical methods; apart from the subprocedure, the framework has low requirement on the quantum capabilities of the party who provides the circuit. We illustrate the subprocedure using a quite simple classical protocol with some privacy tradeoff. For a special case of such protocol, we obtain a scheme similar to blind quantum computation but with the output on a different party. Another way of implementing the subprocedure is to use a recently studied quantum check-based protocol, which has low requirement on the quantum capabilities of both parties. The subprocedure could also be implemented with a classical additive homomorphic encryption scheme. We demonstrate some key steps of the outer part of the framework in a quantum optics experiment. △ Less

Submitted 8 October, 2019; originally announced October 2019.

Comments: 11 pages, 5 figures. Comments are welcome

Demonstration of a 6 State-4 State Reference Frame Independent channel for Quantum Key Distribution

Authors: Ramy Tannous, Zhangdong Ye, Jeongwan Jin, Katanya B. Kuntz, Norbert Lütkenhaus, Thomas Jennewein

Abstract: We study a novel protocol for reference frame independent (RFI) quantum key distribution (QKD) using six states for Alice and four states for Bob, while previous RFI protocols require a six state analyzer for Bob. Our protocol can generate a secure key for any possible phase of the entangled state, provided the variation is small compared to the measurement rate, shown by our numerical key rate an… ▽ More We study a novel protocol for reference frame independent (RFI) quantum key distribution (QKD) using six states for Alice and four states for Bob, while previous RFI protocols require a six state analyzer for Bob. Our protocol can generate a secure key for any possible phase of the entangled state, provided the variation is small compared to the measurement rate, shown by our numerical key rate analysis. We perform a proof-of-principle experiment using polarization entangled photon pairs. In the presence of a varying rotational phase, we obtain a consistently low error rate of less than $4\%$ indicating the feasibility of this protocol for QKD. Our protocol is hence beneficial but not limited to applications in satellite or mobile free-space QKD, where a communication node must limit resources and restrict the number of measured states to four instead of six. △ Less

Submitted 19 November, 2019; v1 submitted 22 May, 2019; originally announced May 2019.

Comments: 5 pages, 3 figures

Journal ref: Appl. Phys. Lett. 115, 211103 (2019)

Genuine time-bin-encoded quantum key distribution over a turbulent depolarizing free-space channel

Authors: Jeongwan Jin, Jean-Philippe Bourgoin, Ramy Tannous, Sascha Agne, Christopher J. Pugh, Katanya B. Kuntz, Brendon L. Higgins, Thomas Jennewein

Abstract: Despite its widespread use in fiber optics, encoding quantum information in photonic time-bin states is usually considered impractical for free-space quantum communication as turbulence-induced spatial distortion impedes the analysis of time-bin states at the receiver. Here, we demonstrate quantum key distribution using time-bin photonic states distorted by turbulence and depolarization during fre… ▽ More Despite its widespread use in fiber optics, encoding quantum information in photonic time-bin states is usually considered impractical for free-space quantum communication as turbulence-induced spatial distortion impedes the analysis of time-bin states at the receiver. Here, we demonstrate quantum key distribution using time-bin photonic states distorted by turbulence and depolarization during free-space transmission. Utilizing a novel analyzer apparatus, we observe stable quantum bit error ratios of 5.32 %, suitable for generating secure keys, despite significant wavefront distortions and polarization fluctuations across a 1.2 km channel. This shows the viability of time-bin quantum communication over long-distance free-space channels, which will simplify direct fiber/free-space interfaces and enable new approaches for practical free-space quantum communication over multi-mode, turbulent, or depolarizing channels. △ Less

Submitted 17 December, 2019; v1 submitted 16 March, 2019; originally announced March 2019.

Journal ref: Opt. Express 27, 37214 (2019)

Phase diagram of the dissipative quantum Ising model on a square lattice

Authors: Jiasen Jin, Alberto Biella, Oscar Viyuela, Cristiano Ciuti, Rosario Fazio, Davide Rossini

Abstract: The competition between interactions and dissipative processes in a quantum many-body system can drive phase transitions of different order. Exploiting a combination of cluster methods and quantum trajectories, we show how the systematic inclusion of (classical and quantum) nonlocal correlations at increasing distances is crucial to determine the structure of the phase diagram, as well as the natu… ▽ More The competition between interactions and dissipative processes in a quantum many-body system can drive phase transitions of different order. Exploiting a combination of cluster methods and quantum trajectories, we show how the systematic inclusion of (classical and quantum) nonlocal correlations at increasing distances is crucial to determine the structure of the phase diagram, as well as the nature of the transitions in strongly interacting spin systems. In practice, we focus on the paradigmatic dissipative quantum Ising model: in contrast to the non-dissipative case, its phase diagram is still a matter of debate in the literature. When dissipation acts along the interaction direction, we predict important quantitative modifications of the position of the first-order transition boundary. In the case of incoherent relaxation in the field direction, our approach confirms the presence of a second-order transition, while does not support the possible existence of multicritical points. Potentially, these results can be tested in up-to date quantum simulators of Rydberg atoms. △ Less

Submitted 17 December, 2018; v1 submitted 18 October, 2018; originally announced October 2018.

Comments: 9 pages, 7 figures. Updated version

Journal ref: Phys. Rev. B 98, 241108 (2018)

Experimental demonstration of quantum walks with initial superposition states

Authors: Qi-Ping Su, Yu Zhang, Li Yu, Jia-Qi Zhou, Jin-Shuang Jin, Xiao-Qiang Xu, Shao-Jie Xiong, QingJun Xu, Zhe Sun, Kefei Chen, Franco Nori, Chui-Ping Yang

Abstract: The preparation of initial superposition states of discrete-time quantum walks (DTQWs) are necessary for the study and applications of DTQWs. In linear optics, it is easy to prepare initial superposition states of the coin, which are always encoded by polarization states; while the preparation of superposition states of the walker is challenging. Based on a novel encoding method, we here propose a… ▽ More The preparation of initial superposition states of discrete-time quantum walks (DTQWs) are necessary for the study and applications of DTQWs. In linear optics, it is easy to prepare initial superposition states of the coin, which are always encoded by polarization states; while the preparation of superposition states of the walker is challenging. Based on a novel encoding method, we here propose a DTQW protocol in linear optics which enables the preparation of arbitrary initial superposition states of the walker and the coin. With this protocol, we report an experimental demonstration of DTQW with the walker initially in superposition states, by using only passive linear-optical elements. The effects of the walker's different initial superposition states on the spread speed of the DTQW and on the entanglement between the coin and the walker are also experimentally investigated, which have not been reported before. When the walker starts with superposition states, we show that the properties of DTQW are very different from those of DTQW starting with a single position. Our findings reveal different properties of DTQW and paves an avenue to study DTQW with arbitrary initial states. Moreover, the encoding method enables one to encode an arbitrary high-dimensional quantum state using a single physical qubit and may be adopted to implement other quantum information tasks. △ Less

Submitted 29 April, 2019; v1 submitted 24 May, 2018; originally announced May 2018.

Comments: 11 pages, 6 figures, accepted in npj Quantum Information

Journal ref: npj Quantum Information 5, 40 (2019)

Echo-Ramsey Interferometry with Motional Quantum States

Authors: D. Hu, L. X. Niu, S. J. Jin, X. Z. Chen, G. J. Dong, J. Schmiedmayer, X. J. Zhou

Abstract: Ramsey interferometers (RIs) using internal electronic or nuclear states find wide applications in science and engineering. We develop a matter wave Ramsey interferometer for motional quantum states exploiting the S- and D-bands of an optical lattice and identify the different de-phasing and de-coherence mechanisms. We implement a band echo technique, employing repeated $π$-pulses. This suppresses… ▽ More Ramsey interferometers (RIs) using internal electronic or nuclear states find wide applications in science and engineering. We develop a matter wave Ramsey interferometer for motional quantum states exploiting the S- and D-bands of an optical lattice and identify the different de-phasing and de-coherence mechanisms. We implement a band echo technique, employing repeated $π$-pulses. This suppresses the de-phasing evolution and significantly increase the coherence time of the motional state interferometer by one order of magnitude. We identify thermal fluctuations as the main mechanism for the remaining decay contrast. Our demonstration of an echo-Ramsey interferometer with motional quantum states in an optical lattice has potential application in the study of quantum many body lattice dynamics, and motional qubits manipulation. △ Less

Submitted 20 December, 2017; originally announced December 2017.

Comments: 9 pages, 6 figures

Journal ref: Communication Physics 1, 29 (2018)

Quantum correlations and limit cycles in the driven-dissipative Heisenberg lattice

Authors: E. T. Owen, J. Jin, D. Rossini, R. Fazio, M. J. Hartmann

Abstract: Driven-dissipative quantum many-body systems have attracted increasing interest in recent years as they lead to novel classes of quantum many-body phenomena. In particular, mean-field calculations predict limit cycle phases, slow oscillations instead of stationary states, in the long-time limit for a number of driven-dissipative quantum many-body systems. Using a cluster mean-field and a self-cons… ▽ More Driven-dissipative quantum many-body systems have attracted increasing interest in recent years as they lead to novel classes of quantum many-body phenomena. In particular, mean-field calculations predict limit cycle phases, slow oscillations instead of stationary states, in the long-time limit for a number of driven-dissipative quantum many-body systems. Using a cluster mean-field and a self-consistent Mori projector approach, we explore the persistence of such limit cycles as short range quantum correlations are taken into account in a driven-dissipative Heisenberg model. △ Less

Submitted 26 March, 2018; v1 submitted 30 November, 2017; originally announced November 2017.

Comments: 13 pages, 7 figures

Journal ref: New J. Phys., 20, 045004 (2018)

Non-Markovianity in a collision model with environmental block

Authors: Jiasen Jin, Chang-shui Yu

Abstract: We present an extended collision model to simulate the dynamics of an open quantum system. In our model, the unit to represent the environment is, instead of a single particle, a block which consists of a number of environment particles. The introduced blocks enable us to study the effects of different strategies of system-environment interactions and states of the blocks on the non-Markovianities… ▽ More We present an extended collision model to simulate the dynamics of an open quantum system. In our model, the unit to represent the environment is, instead of a single particle, a block which consists of a number of environment particles. The introduced blocks enable us to study the effects of different strategies of system-environment interactions and states of the blocks on the non-Markovianities. We demonstrate our idea in the Gaussian channels of an all-optical system and derive a necessary and sufficient condition of non-Markovianity for such channels. Moreover, we show the equivalence of our criterion to the non-Markovian quantum jump in the simulation of the pure damping process of a single-mode field. We also show that the non-Markovianity of the channel working in the strategy that the system collides with environmental particles in each block in a certain order will be affected by the size of the block and the embedded entanglement and the effects of heating and squeezing the vacuum environmental state will quantitatively enhance the non-Markovianity. △ Less

Submitted 9 May, 2018; v1 submitted 19 October, 2017; originally announced October 2017.

Comments: 9 pages, 6 figures, accepted version

Journal ref: New J. Phys. 20, 053026 (2018)

Linked cluster expansions for open quantum systems on a lattice

Authors: Alberto Biella, Jiasen Jin, Oscar Viyuela, Cristiano Ciuti, Rosario Fazio, Davide Rossini

Abstract: We propose a generalization of the linked-cluster expansions to study driven-dissipative quantum lattice models, directly accessing the thermodynamic limit of the system. Our method leads to the evaluation of the desired extensive property onto small connected clusters of a given size and topology. We first test this approach on the isotropic spin-1/2 Hamiltonian in two dimensions, where each spin… ▽ More We propose a generalization of the linked-cluster expansions to study driven-dissipative quantum lattice models, directly accessing the thermodynamic limit of the system. Our method leads to the evaluation of the desired extensive property onto small connected clusters of a given size and topology. We first test this approach on the isotropic spin-1/2 Hamiltonian in two dimensions, where each spin is coupled to an independent environment that induces incoherent spin flips. Then we apply it to the study of an anisotropic model displaying a dissipative phase transition from a magnetically ordered to a disordered phase. By means of a Padé analysis on the series expansions for the average magnetization, we provide a viable route to locate the phase transition and to extrapolate the critical exponent for the magnetic susceptibility. △ Less

Submitted 12 November, 2017; v1 submitted 29 August, 2017; originally announced August 2017.

Comments: 10 pages, 5 figures

Journal ref: Phys. Rev. B 97, 035103 (2018)

Experimental simulation of quantum temporal steering beyond rotating-wave approximation

Authors: Shao-Jie Xiong, Yu Zhang, Zhe Sun, Li Yu, Jinshuang Jin, Xiao-Qiang Xu, Jin-Ming Liu, Kefei Chen, Chui-Ping Yang

Abstract: Characterizing the dynamics of open systems usually starts with a perturbative theory and involves various approximations, such as the Born, Markov and rotating-wave approximation (RWA). However, the approximation approaches could introduce more or less incompleteness in describing the bath behaviors. Here, we consider a quantum channel, which is modeled by a qubit (a two-level system) interacting… ▽ More Characterizing the dynamics of open systems usually starts with a perturbative theory and involves various approximations, such as the Born, Markov and rotating-wave approximation (RWA). However, the approximation approaches could introduce more or less incompleteness in describing the bath behaviors. Here, we consider a quantum channel, which is modeled by a qubit (a two-level system) interacting with a bosonic bath. Unlike the traditional works, we experimentally simulate the system-bath interaction without applying the Born, Markov, and rotating-wave approximations. To our knowledge, this is the first experimental simulation of the quantum channels without any approximations mentioned above, by using linear optical devices. The results are quite useful and interesting, which not only reveal the effect of the counter-rotating terms but also present a more accurate picture of the quantum channel dynamics. Besides, we experimentally investigate the dynamics of the quantum temporal steering (TS), i.e., a temporal analogue of Einstein-Podolsky-Rosen steering. The experimental and theoretical results are in good agreement and show that the counter-rotating terms significantly influence the TS dynamics. When one monogamously associates TS with the security of the cryptographic protocols (e.g., BB84), our experimental tests reveal that the channels based on RWA will provide exaggerated security durations, while they are actually insecure in non-RWA channel cases. This implies that doing RWA may result in a risk for the security of quantum key distribution. Our findings are expected to have useful applications in secure quantum communications and future interesting TS studies. △ Less

Submitted 31 March, 2017; v1 submitted 4 March, 2017; originally announced March 2017.

Comments: 20 pages, 3 figures

Journal ref: Optica 4, 1065-1072 (2017)

Airborne demonstration of a quantum key distribution receiver payload

Authors: Christopher J. Pugh, Sarah Kaiser, Jean-Philippe Bourgoin, Jeongwan Jin, Nigar Sultana, Sascha Agne, Elena Anisimova, Vadim Makarov, Eric Choi, Brendon L. Higgins, Thomas Jennewein

Abstract: Satellite-based quantum terminals are a feasible way to extend the reach of quantum communication protocols such as quantum key distribution (QKD) to the global scale. To that end, prior demonstrations have shown QKD transmissions from airborne platforms to receivers on ground, but none have shown QKD transmissions from ground to a moving aircraft, the latter scenario having simplicity and flexibi… ▽ More Satellite-based quantum terminals are a feasible way to extend the reach of quantum communication protocols such as quantum key distribution (QKD) to the global scale. To that end, prior demonstrations have shown QKD transmissions from airborne platforms to receivers on ground, but none have shown QKD transmissions from ground to a moving aircraft, the latter scenario having simplicity and flexibility advantages for a hypothetical satellite. Here, we demonstrate QKD from a ground transmitter to a receiver prototype mounted on an airplane in flight. We have specifically designed our receiver prototype to consist of many components that are compatible with the environment and resource constraints of a satellite. Coupled with our relocatable ground station system, optical links with distances of 3-10 km were maintained and quantum signals transmitted while traversing angular rates similar to those observed of low-Earth-orbit satellites. For some passes of the aircraft over the ground station, links were established within 10 s of position data transmission, and with link times of a few minutes and received quantum bit error rates typically 3-5%, we generated secure keys up to 868 kb in length. By successfully generating secure keys over several different pass configurations, we demonstrate the viability of technology that constitutes a quantum receiver satellite payload and provide a blueprint for future satellite missions to build upon. △ Less

Submitted 9 June, 2017; v1 submitted 19 December, 2016; originally announced December 2016.

Comments: 16 pages, 5 figures, Updated pointing figures, Added references

Journal ref: Quantum Sci. Technol. 2, 024009 (2017)

Observation of genuine three-photon interference

Authors: Sascha Agne, Thomas Kauten, Jeongwan Jin, Evan Meyer-Scott, Jeff Z. Salvail, Deny R. Hamel, Kevin J. Resch, Gregor Weihs, Thomas Jennewein

Abstract: Multiparticle quantum interference is critical for our understanding and exploitation of quantum information, and for fundamental tests of quantum mechanics. A remarkable example of multi-partite correlations is exhibited by the Greenberger-Horne-Zeilinger (GHZ) state. In a GHZ state, three particles are correlated while no pairwise correlation is found. The manifestation of these strong correlati… ▽ More Multiparticle quantum interference is critical for our understanding and exploitation of quantum information, and for fundamental tests of quantum mechanics. A remarkable example of multi-partite correlations is exhibited by the Greenberger-Horne-Zeilinger (GHZ) state. In a GHZ state, three particles are correlated while no pairwise correlation is found. The manifestation of these strong correlations in an interferometric setting has been studied theoretically since 1990 but no three-photon GHZ interferometer has been realized experimentally. Here we demonstrate three-photon interference that does not originate from two-photon or single photon interference. We observe phase-dependent variation of three-photon coincidences with 90.5 \pm 5.0 % visibility in a generalized Franson interferometer using energy-time entangled photon triplets. The demonstration of these strong correlations in an interferometric setting provides new avenues for multiphoton interferometry, fundamental tests of quantum mechanics and quantum information applications in higher dimensions. △ Less

Submitted 19 April, 2017; v1 submitted 23 September, 2016; originally announced September 2016.

Comments: 7 pages, 7 figures

Journal ref: Phys. Rev. Lett. 118, 153602 (2017)

Cluster mean-field approach to the steady-state phase diagram of dissipative spin systems

Authors: Jiasen Jin, Alberto Biella, Oscar Viyuela, Leonardo Mazza, Jonathan Keeling, Rosario Fazio, Davide Rossini

Abstract: We show that short-range correlations have a dramatic impact on the steady-state phase diagram of quantum driven-dissipative systems. This effect, never observed in equilibrium, follows from the fact that ordering in the steady state is of dynamical origin, and is established only at very long times, whereas in thermodynamic equilibrium it arises from the properties of the (free) energy. To this e… ▽ More We show that short-range correlations have a dramatic impact on the steady-state phase diagram of quantum driven-dissipative systems. This effect, never observed in equilibrium, follows from the fact that ordering in the steady state is of dynamical origin, and is established only at very long times, whereas in thermodynamic equilibrium it arises from the properties of the (free) energy. To this end, by combining the cluster methods extensively used in equilibrium phase transitions to quantum trajectories and tensor-network techniques, we extend them to nonequilibrium phase transitions in dissipative many-body systems. We analyze in detail a model of spin-1=2 on a lattice interacting through an XYZ Hamiltonian, each of them coupled to an independent environment that induces incoherent spin flips. In the steady-state phase diagram derived from our cluster approach, the location of the phase boundaries and even its topology radically change, introducing reentrance of the paramagnetic phase as compared to the single-site mean field where correlations are neglected. Furthermore, a stability analysis of the cluster mean field indicates a susceptibility towards a possible incommensurate ordering, not present if short-range correlations are ignored. △ Less

Submitted 28 July, 2016; v1 submitted 21 February, 2016; originally announced February 2016.

Comments: Published version. 18 pages, 15 figures

Journal ref: Phys. Rev. X 6, 031011 (2016)

Non-Markovian correlation functions for open quantum systems

Authors: Jinshuang Jin, Christian Karlewski, Michael Marthaler

Abstract: Beyond the conventional quantum regression theorem, a general formula for non-Markovian correlation functions of arbitrary system operators both in the time- and frequency-domain is given. We approach the problem by transforming the conventional time-nonlocal master equation into dispersed time-local equations-of-motion. The validity of our approximations is discussed and we find that the non-Mark… ▽ More Beyond the conventional quantum regression theorem, a general formula for non-Markovian correlation functions of arbitrary system operators both in the time- and frequency-domain is given. We approach the problem by transforming the conventional time-nonlocal master equation into dispersed time-local equations-of-motion. The validity of our approximations is discussed and we find that the non-Markovian terms have to be included for short times. While calculations of the density matrix at short times suffer from the initial value problem, a correlation function has a well defined initial state. The resulting formula for the non-Markovian correlation function has a simple structure and is as convenient in its application as the conventional quantum regression theorem for the Markovian case. For illustrations, we apply our method to investigate the spectrum of the current fluctuations of interacting quantum dots contacted with two electrodes. The corresponding non-Markovian characteristics are demonstrated. △ Less

Submitted 6 December, 2015; originally announced December 2015.

Comments: 11 pages, 5 figures

Demonstration of analyzers for multimode photonic time-bin qubits

Authors: Jeongwan Jin, Sascha Agne, Jean-Philippe Bourgoin, Yanbao Zhang, Norbert Lütkenhaus, Thomas Jennewein

Abstract: We demonstrate two approaches for unbalanced interferometers as time-bin qubit analyzers for quantum communication, robust against mode distortions and polarization effects as expected from free-space quantum communication systems including wavefront deformations, path fluctuations, pointing errors, and optical elements. Despite strong spatial and temporal distortions of the optical mode of a time… ▽ More We demonstrate two approaches for unbalanced interferometers as time-bin qubit analyzers for quantum communication, robust against mode distortions and polarization effects as expected from free-space quantum communication systems including wavefront deformations, path fluctuations, pointing errors, and optical elements. Despite strong spatial and temporal distortions of the optical mode of a time-bin qubit, entangled with a separate polarization qubit, we verify entanglement using the Negative Partial Transpose, with the measured visibility of up to 0.85$\pm$0.01. The robustness of the analyzers is further demonstrated for various angles of incidence up to 0.2$^{\circ}$. The output of the interferometers is coupled into multimode fiber yielding a high system throughput of 0.74. Therefore, these analyzers are suitable and efficient for quantum communication over multimode optical channels. △ Less

Submitted 27 April, 2018; v1 submitted 24 September, 2015; originally announced September 2015.

Journal ref: Phys. Rev. A 97, 043847 (2018)

A telecom-wavelength atomic quantum memory in optical fiber for heralded polarization qubits

Authors: Jeongwan Jin, Erhan Saglamyurek, Marcel. li Grimau Puigibert, Varun B. Verma, Francesco Marsili, Sae Woo Nam, Daniel Oblak, Wolfgang Tittel

Abstract: Photon-based quantum information processing promises new technologies including optical quantum computing, quantum cryptography, and distributed quantum networks. Polarization-encoded photons at telecommunication wavelengths provide a compelling platform for practical realization of these technologies. However, despite important success towards building elementary components compatible with this p… ▽ More Photon-based quantum information processing promises new technologies including optical quantum computing, quantum cryptography, and distributed quantum networks. Polarization-encoded photons at telecommunication wavelengths provide a compelling platform for practical realization of these technologies. However, despite important success towards building elementary components compatible with this platform, including sources of entangled photons, efficient single photon detectors, and on-chip quantum circuits, a missing element has been atomic quantum memory that directly allows for reversible mapping of quantum states encoded in the polarization degree of a telecom-wavelength photon. Here we demonstrate the quantum storage and retrieval of polarization states of heralded single-photons at telecom-wavelength by implementing the atomic frequency comb protocol in an ensemble of erbium atoms doped into an optical fiber. Despite remaining limitations in our proof-of-principle demonstration such as small storage efficiency and storage time, our broadband light-matter interface reveals the potential for use in future quantum information processing. △ Less

Submitted 14 June, 2015; originally announced June 2015.

Comments: The first two authors contributed equally to this work

Journal ref: Phys. Rev. Lett. 115, 140501 (2015)