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Resonantly pumped bright-triplet exciton lasing in caesium lead bromide perovskites
Authors:
Guanhua Ying,
Tristan Farrow,
Atanu Jana,
Hanbo Shao,
Hyunsik Im,
Vitaly Osokin,
Seung Bin Baek,
Mutibah Alanazi,
Sanjit Karmakar,
Manas Mukherjee,
Youngsin Park,
Robert A. Taylor
Abstract:
The surprising recent observation of highly emissive triplet-states in lead halide perovskites accounts for their orders-of-magnitude brighter optical signals and high quantum efficiencies compared to other semiconductors. This makes them attractive for future optoelectronic applications, especially in bright low-threshold nano-lasers. Whilst non-resonantly pumped lasing from all-inorganic lead-ha…
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The surprising recent observation of highly emissive triplet-states in lead halide perovskites accounts for their orders-of-magnitude brighter optical signals and high quantum efficiencies compared to other semiconductors. This makes them attractive for future optoelectronic applications, especially in bright low-threshold nano-lasers. Whilst non-resonantly pumped lasing from all-inorganic lead-halide perovskites is now well-established as an attractive pathway to scalable low-power laser sources for nano-optoelectronics, here we showcase a resonant optical pumping scheme on a fast triplet-state in CsPbBr3 nanocrystals. The scheme allows us to realize a polarized triplet-laser source that dramatically enhances the coherent signal by one order of magnitude whilst suppressing non-coherent contributions. The result is a source with highly attractive technological characteristics including a bright and polarized signal, and a high stimulated-to-spontaneous emission signal contrast that can be filtered to enhance spectral purity. The emission is generated by pumping selectively on a weakly-confined excitonic state with a Bohr radius ~10 nm in the nanocrystals. The exciton fine-structure is revealed by the energy-splitting resulting from confinement in nanocrystals with tetragonal symmetry. We use a linear polarizer to resolve two-fold non-degenerate sub-levels in the triplet exciton and use photoluminescence excitation spectroscopy to determine the energy of the state before pumping it resonantly.
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Submitted 14 July, 2021;
originally announced July 2021.
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Stochastic single flux quantum neuromorphic computing using magnetically tunable Josephson junctions
Authors:
S. E. Russek,
C. A. Donnelly,
M. L. Schneider,
B. Baek,
M. R. Pufall,
W. H. Rippard,
P. F. Hopkins,
P. D. Dresselhaus,
S. P. Benz
Abstract:
Single flux quantum (SFQ) circuits form a natural neuromorphic technology with SFQ pulses and superconducting transmission lines simulating action potentials and axons, respectively. Here we present a new component, magnetic Josephson junctions, that have a tunablility and re-configurability that was lacking from previous SFQ neuromorphic circuits. The nanoscale magnetic structure acts as a tunabl…
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Single flux quantum (SFQ) circuits form a natural neuromorphic technology with SFQ pulses and superconducting transmission lines simulating action potentials and axons, respectively. Here we present a new component, magnetic Josephson junctions, that have a tunablility and re-configurability that was lacking from previous SFQ neuromorphic circuits. The nanoscale magnetic structure acts as a tunable synaptic constituent that modifies the junction critical current. These circuits can operate near the thermal limit where stochastic firing of the neurons is an essential component of the technology. This technology has the ability to create complex neural systems with greater than 10^21 neural firings per second with approximately 1 W dissipation.
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Submitted 12 November, 2016;
originally announced December 2016.
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Spin-transfer torque switching in nanopillar superconducting-magnetic hybrid Josephson junctions
Authors:
Burm Baek,
William H. Rippard,
Matthew R. Pufall,
Samuel P. Benz,
Stephen E. Russek,
Horst Rogalla,
Paul D. Dresselhaus
Abstract:
The combination of superconducting and magnetic materials to create novel superconducting devices has been motivated by the discovery of Josephson critical current (Ics) oscillations as a function of magnetic layer thickness and the demonstration of devices with switchable critical currents. However, none of the hybrid devices have shown any spintronic effects, such as spin-transfer torque, which…
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The combination of superconducting and magnetic materials to create novel superconducting devices has been motivated by the discovery of Josephson critical current (Ics) oscillations as a function of magnetic layer thickness and the demonstration of devices with switchable critical currents. However, none of the hybrid devices have shown any spintronic effects, such as spin-transfer torque, which are currently used in room-temperature magnetic devices, including spin-transfer torque random-access memory and spin-torque nano-oscillators. We have developed nanopillar Josephson junctions with a minimum feature size of 50 nm and magnetic barriers exhibiting magnetic pseudo-spin-valve behavior at 4 K. These devices allow current-induced magnetization switching that results in 20-fold changes in Ics. The current-induced magnetic switching is consistent with spin-transfer torque models for room-temperature magnetic devices. Our work demonstrates that devices that combine superconducting and spintronic functions show promise for the development of a nanoscale, nonvolatile, cryogenic memory technology.
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Submitted 16 October, 2014;
originally announced October 2014.
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Hybrid superconducting-magnetic memory device using competing order parameters
Authors:
Burm Baek,
William H. Rippard,
Samuel P. Benz,
Stephen E. Russek,
Paul D. Dresselhaus
Abstract:
Superconducting devices, which rely on modulating a complex superconducting order parameter in a Josephson junction, have been developed for low power logic operations, high-frequency oscillators, and exquisite magnetic field sensors. Magnetic devices, which rely on the modulation of a local vector order parameter- the local magnetic moment, have been used as memory elements, high-frequency spin-t…
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Superconducting devices, which rely on modulating a complex superconducting order parameter in a Josephson junction, have been developed for low power logic operations, high-frequency oscillators, and exquisite magnetic field sensors. Magnetic devices, which rely on the modulation of a local vector order parameter- the local magnetic moment, have been used as memory elements, high-frequency spin-transfer oscillators, and magnetic field sensors. In a hybrid superconducting-magnetic device, these two order parameters compete, with one type of order suppressing the other. Recent interest in ultra-low-power, high-density cryogenic memories has spurred new interest in merging superconducting and magnetic behavior so as to exploit these two competing order parameters to produce novel switching elements. Here, we describe a reconfigurable two-layer magnetic spin valve integrated within a Josephson junction. Our measurements separate the suppression in the superconducting coupling due to the exchange field in the magnetic layers, which causes depairing of the supercurrent, from the suppression due to the magnetic field generated by the magnetic layers. The exchange field suppression of the superconducting order parameter is a tunable and switchable behavior that is also scalable to nanometer device dimensions. These devices are the first to demonstrate nonvolatile, size-independent switching of the Josephson coupling, in both magnitude and phase, and they may allow for the first nanoscale superconducting memory devices.
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Submitted 29 October, 2013; v1 submitted 8 October, 2013;
originally announced October 2013.
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Detecting Single Infrared Photons with 93% System Efficiency
Authors:
F. Marsili,
V. B. Verma,
J. A. Stern,
S. Harrington,
A. E. Lita,
T. Gerrits,
I. Vayshenker,
B. Baek,
M. D. Shaw,
R. P. Mirin,
S. W. Nam
Abstract:
Single-photon detectors (SPDs) at near infrared wavelengths with high system detection efficiency (> 90%), low dark count rate (< 1 counts per second, cps), low timing jitter (< 100 ps), and short reset time (< 100 ns) would enable landmark experiments in a variety of fields. Although some of the existing approaches to single-photon detection fulfill one or two of the above specifications, to date…
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Single-photon detectors (SPDs) at near infrared wavelengths with high system detection efficiency (> 90%), low dark count rate (< 1 counts per second, cps), low timing jitter (< 100 ps), and short reset time (< 100 ns) would enable landmark experiments in a variety of fields. Although some of the existing approaches to single-photon detection fulfill one or two of the above specifications, to date no detector has met all of the specifications simultaneously. Here we report on a fiber-coupled single-photon-detection system employing superconducting nanowire single photon detectors (SNSPDs) that closely approaches the ideal performance of SPDs. Our detector system has a system detection efficiency (SDE), including optical coupling losses, greater than 90% in the wavelength range λ= 1520-1610 nm; device dark count rate (measured with the device shielded from room-temperature blackbody radiation) of ~ 0.01 cps; timing jitter of ~ 150 ps FWHM; and reset time of 40 ns.
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Submitted 25 September, 2012;
originally announced September 2012.
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Operating quantum waveguide circuits with superconducting single-photon detectors
Authors:
C. M. Natarajan,
A. Peruzzo,
S. Miki,
M. Sasaki,
Z. Wang,
B. Baek,
S. Nam,
R. H. Hadfield,
J. L. O'Brien
Abstract:
Advanced quantum information science and technology (QIST) applications place exacting de- mands on optical components. Quantum waveguide circuits offer a route to scalable QIST on a chip. Superconducting single-photon detectors (SSPDs) provide infrared single-photon sensitivity combined with low dark counts and picosecond timing resolution. In this study we bring these two technologies together.…
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Advanced quantum information science and technology (QIST) applications place exacting de- mands on optical components. Quantum waveguide circuits offer a route to scalable QIST on a chip. Superconducting single-photon detectors (SSPDs) provide infrared single-photon sensitivity combined with low dark counts and picosecond timing resolution. In this study we bring these two technologies together. Using SSPDs we observe a two-photon interference visibility of 92.3\pm1.0% in a silica-on-silicon waveguide directional coupler at \lamda = 804 nm-higher than that measured with silicon detectors (89.9\pm0.3%). We further operated controlled-NOT gate and quantum metrology circuits with SSPDs. These demonstrations present a clear path to telecom-wavelength quantum waveguide circuits.
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Submitted 24 March, 2010;
originally announced March 2010.