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Real-time vacuum-state quantum random number generator on a chip
Authors:
Guan-Ru Qiao,
Bing Bai,
Zi-Xuan Weng,
Han-Shen Chen,
Wei Zheng,
Zhi-Yuan Zheng,
You-Qi Nie,
Jun Zhang,
Jian-Wei Pan
Abstract:
Quantum random number generators (QRNGs) produce true random numbers, which are guaranteed by the fundamental principles of quantum physics. Miniaturization of QRNGs is crucial for a wide range of communication and cryptography applications. Here, we first report a fully functional QRNG chip based on vacuum-state fluctuations, with dimensions of 16.6 mm x 7.8 mm. The quantum entropy source, which…
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Quantum random number generators (QRNGs) produce true random numbers, which are guaranteed by the fundamental principles of quantum physics. Miniaturization of QRNGs is crucial for a wide range of communication and cryptography applications. Here, we first report a fully functional QRNG chip based on vacuum-state fluctuations, with dimensions of 16.6 mm x 7.8 mm. The quantum entropy source, which is achieved via hybrid photonic integration with a SiO2 waveguide, generates raw quantum random numbers. The hybrid photonic and electrical components are assembled into a compact ceramic package using system-in-package technology. A microcontroller unit acquires the raw data and outputs the processed quantum random numbers via a serial peripheral interface. According to the characterization results, the QRNG chip achieves a constant real-time output rate of 5.2 Mbps across the industrial temperature range of -40°C to 85°C, making it suitable for practical applications.
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Submitted 16 September, 2025;
originally announced September 2025.
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White Gaussian Noise Generation with a Vacuum State Quantum Entropy Source Chip
Authors:
Guan-Ru Qiao,
Bing Bai,
Zi-Xuan Weng,
Jia-Ying Wu,
You-Qi Nie,
Jun Zhang
Abstract:
White Gaussian noise (WGN) is widely used in communication system testing, physical modeling, Monte Carlo simulations, and electronic countermeasures. WGN generation relies heavily on random numbers. In this work, we present an implementation of WGN generation utilizing a quantum entropy source chip for the first time. A photonic integrated chip based on the vacuum state scheme generates quantum r…
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White Gaussian noise (WGN) is widely used in communication system testing, physical modeling, Monte Carlo simulations, and electronic countermeasures. WGN generation relies heavily on random numbers. In this work, we present an implementation of WGN generation utilizing a quantum entropy source chip for the first time. A photonic integrated chip based on the vacuum state scheme generates quantum random numbers at a real-time output rate of up to 6.4 Gbps. A hardware-based inversion method converts uniform quantum random numbers into Gaussian random numbers using the inverse cumulative distribution function. Subsequently, the WGN signal is generated through a digital-to-analog converter and amplifiers. The WGN generator is characterized by a bandwidth of 230 MHz, a crest factor as high as 6.2, and an adjustable peak-to-peak range of 2.5 V. This work introduces a novel approach to WGN generation with information-theory provable quantum random numbers to enhance system security.
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Submitted 6 March, 2025;
originally announced March 2025.
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Measurement-device-independent quantum random number generation over 23 Mbps with imperfect single-photon sources
Authors:
You-Qi Nie,
Hongyi Zhou,
Bing Bai,
Qi Xu,
Xiongfeng Ma,
Jun Zhang,
Jian-Wei Pan
Abstract:
Quantum randomness relies heavily on the accurate characterization of the generator implementation, where the device imperfection or inaccurate characterization can lead to incorrect entropy estimation and practical bias, significantly affecting the reliability of the generated randomness. Measurement-device-independent (MDI) quantum random number generation (QRNG) endeavors to produce certified r…
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Quantum randomness relies heavily on the accurate characterization of the generator implementation, where the device imperfection or inaccurate characterization can lead to incorrect entropy estimation and practical bias, significantly affecting the reliability of the generated randomness. Measurement-device-independent (MDI) quantum random number generation (QRNG) endeavors to produce certified randomness, utilizing uncharacterized and untrusted measurement devices that are vulnerable to numerous attack schemes targeting measurement loopholes. However, existing implementations have shown insufficient performance thus far. Here, we propose a high-speed MDI-QRNG scheme based on a robust measurement tomography approach against the imperfection of single-photon sources. Compared with the conventional approach, the decoy-state method is introduced to obtain more accurate tomography results and a tighter lower bound of randomness. Finally, by using a high-speed time-bin encoding system, we experimentally demonstrated the scheme and obtained a reliable min-entropy lower bound of $7.37 \times 10^{-2}$ bits per pulse, corresponding to a generation rate over 23 Mbps, which substantially outperforms the existing realizations and makes a record in discrete-variable semi-device-independent QRNGs.
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Submitted 15 March, 2024;
originally announced March 2024.
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Experimental full network nonlocality with independent sources and strict locality constraints
Authors:
Xue-Mei Gu,
Liang Huang,
Alejandro Pozas-Kerstjens,
Yang-Fan Jiang,
Dian Wu,
Bing Bai,
Qi-Chao Sun,
Ming-Cheng Chen,
Jun Zhang,
Sixia Yu,
Qiang Zhang,
Chao-Yang Lu,
Jian-Wei Pan
Abstract:
Nonlocality arising in networks composed of several independent sources gives rise to phenomena radically different from that in standard Bell scenarios. Over the years, the phenomenon of network nonlocality in the entanglement-swapping scenario has been well investigated and demonstrated. However, it is known that violations of the so-called bilocality inequality used in previous experimental dem…
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Nonlocality arising in networks composed of several independent sources gives rise to phenomena radically different from that in standard Bell scenarios. Over the years, the phenomenon of network nonlocality in the entanglement-swapping scenario has been well investigated and demonstrated. However, it is known that violations of the so-called bilocality inequality used in previous experimental demonstrations cannot be used to certify the non-classicality of their sources. This has put forward a stronger concept for nonlocality in networks, called full network nonlocality. Here, we experimentally observe full network nonlocal correlations in a network where the source-independence, locality, and measurement-independence loopholes are closed. This is ensured by employing two independent sources, rapid setting generation, and space-like separations of relevant events. Our experiment violates known inequalities characterizing non-full network nonlocal correlations by over five standard deviations, certifying the absence of classical sources in the realization.
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Submitted 12 May, 2023; v1 submitted 5 February, 2023;
originally announced February 2023.
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Experimental demonstration of genuine tripartite nonlocality under strict locality conditions
Authors:
Liang Huang,
Xue-Mei Gu,
Yang-Fan Jiang,
Dian Wu,
Bing Bai,
Ming-Cheng Chen,
Qi-Chao Sun,
Jun Zhang,
Sixia Yu,
Qiang Zhang,
Chao-Yang Lu,
Jian-Wei Pan
Abstract:
Nonlocality captures one of the counterintuitive features of nature that defies classical intuition. Recent investigations reveal that our physical world's nonlocality is at least tripartite; i.e., genuinely tripartite nonlocal correlations in nature cannot be reproduced by any causal theory involving bipartite nonclassical resources and unlimited shared randomness. Here, by allowing the fair samp…
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Nonlocality captures one of the counterintuitive features of nature that defies classical intuition. Recent investigations reveal that our physical world's nonlocality is at least tripartite; i.e., genuinely tripartite nonlocal correlations in nature cannot be reproduced by any causal theory involving bipartite nonclassical resources and unlimited shared randomness. Here, by allowing the fair sampling assumption and postselection, we experimentally demonstrate such genuine tripartite nonlocality in a network under strict locality constraints that are ensured by spacelike separating all relevant events and employing fast quantum random number generators and high-speed polarization measurements. In particular, for a photonic quantum triangular network we observe a locality-loophole-free violation of the Bell-type inequality by 7.57 standard deviations for a postselected tripartite Greenberger-Horne-Zeilinger state of fidelity $(93.13 \pm 0.24)\%$, which convincingly disproves the possibility of simulating genuine tripartite nonlocality by bipartite nonlocal resources with globally shared randomness.
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Submitted 3 August, 2022; v1 submitted 2 March, 2022;
originally announced March 2022.
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Experimental refutation of real-valued quantum mechanics under strict locality conditions
Authors:
Dian Wu,
Yang-Fan Jiang,
Xue-Mei Gu,
Liang Huang,
Bing Bai,
Qi-Chao Sun,
Si-Qiu Gong,
Yingqiu Mao,
Han-Sen Zhong,
Ming-Cheng Chen,
Jun Zhang,
Qiang Zhang,
Chao-Yang Lu,
Jian-Wei Pan
Abstract:
Physicists describe nature using mathematics as the natural language, and for quantum mechanics, it prefers to use complex numbers. However, whether complex numbers are really necessary for the theory has been debated ever since its birth. Recently, it has been shown that a three-party correlation created in entanglement swapping scenarios comprising independent states and measurements cannot be r…
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Physicists describe nature using mathematics as the natural language, and for quantum mechanics, it prefers to use complex numbers. However, whether complex numbers are really necessary for the theory has been debated ever since its birth. Recently, it has been shown that a three-party correlation created in entanglement swapping scenarios comprising independent states and measurements cannot be reproduced using only real numbers. Previous experiments have conceptually supported the predication, yet not satisfying the independent state preparations and measurements simultaneously. Here, we implement such a test with two truly independent sources delivering entangled photons to three parties under strict locality conditions. By employing fast quantum random number generators and high-speed polarization measurements, we space-like separate all relevant events to ensure independent state preparations and measurements, and close locality loopholes simultaneously. Our results violate the real number bound of 7.66 by 5.30 standard deviations, hence rejecting the universal validity of the real-valued quantum mechanics to describe nature.
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Submitted 9 February, 2022; v1 submitted 11 January, 2022;
originally announced January 2022.
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Device-Independent-Quantum-Randomness-Enhanced Zero-Knowledge Proof
Authors:
Cheng-Long Li,
Kai-Yi Zhang,
Xingjian Zhang,
Kui-Xing Yang,
Yu Han,
Su-Yi Cheng,
Hongrui Cui,
Wen-Zhao Liu,
Ming-Han Li,
Yang Liu,
Bing Bai,
Hai-Hao Dong,
Jun Zhang,
Xiongfeng Ma,
Yu Yu,
Jingyun Fan,
Qiang Zhang,
Jian-Wei Pan
Abstract:
Zero-knowledge proof (ZKP) is a fundamental cryptographic primitive that allows a prover to convince a verifier of the validity of a statement without leaking any further information. As an efficient variant of ZKP, non-interactive zero-knowledge proof (NIZKP) adopting the Fiat-Shamir heuristic is essential to a wide spectrum of applications, such as federated learning, blockchain and social netwo…
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Zero-knowledge proof (ZKP) is a fundamental cryptographic primitive that allows a prover to convince a verifier of the validity of a statement without leaking any further information. As an efficient variant of ZKP, non-interactive zero-knowledge proof (NIZKP) adopting the Fiat-Shamir heuristic is essential to a wide spectrum of applications, such as federated learning, blockchain and social networks. However, the heuristic is typically built upon the random oracle model making ideal assumptions about hash functions, which does not hold in reality and thus undermines the security of the protocol. Here, we present a quantum resolution to the problem. Instead of resorting to a random oracle model, we implement a quantum randomness service. This service generates random numbers certified by the loophole-free Bell test and delivers them with postquantum cryptography (PQC) authentication. Employing this service, we conceive and implement a NIZKP of the three-colouring problem. By bridging together three prominent research themes, quantum non-locality, PQC and ZKP, we anticipate this work to open a new paradigm of quantum information science.
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Submitted 12 November, 2021;
originally announced November 2021.
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18.8 Gbps real-time quantum random number generator with a photonic integrated chip
Authors:
Bing Bai,
Jianyao Huang,
Guan-Ru Qiao,
You-Qi Nie,
Weijie Tang,
Tao Chu,
Jun Zhang,
Jian-Wei Pan
Abstract:
Quantum random number generators (QRNGs) can produce true random numbers. Yet, the two most important QRNG parameters highly desired for practical applications, i.e., speed and size, have to be compromised during implementations. Here, we present the fastest and miniaturized QRNG with a record real-time output rate as high as 18.8 Gbps by combining a photonic integrated chip and the technology of…
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Quantum random number generators (QRNGs) can produce true random numbers. Yet, the two most important QRNG parameters highly desired for practical applications, i.e., speed and size, have to be compromised during implementations. Here, we present the fastest and miniaturized QRNG with a record real-time output rate as high as 18.8 Gbps by combining a photonic integrated chip and the technology of optimized randomness extraction. We assemble the photonic integrated circuit designed for vacuum state QRNG implementation, InGaAs homodyne detector and high-bandwidth transimpedance amplifier into a single chip using hybrid packaging, which exhibits the excellent characteristics of integration and high-frequency response. With a sample rate of 2.5 GSa/s in a 10-bit analog-to-digital converter and subsequent paralleled postprocessing in a field programmable gate array, the QRNG outputs ultrafast random bitstreams via a fiber optic transceiver, whose real-time speed is validated in a personal computer.
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Submitted 27 May, 2021;
originally announced May 2021.
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Measurement-Device-Independent Verification of a Quantum Memory
Authors:
Yong Yu,
Peng-Fei Sun,
Yu-Zhe Zhang,
Bing Bai,
Yu-Qiang Fang,
Xi-Yu Luo,
Zi-Ye An,
Jun Li,
Jun Zhang,
Feihu Xu,
Xiao-Hui Bao,
Jian-Wei Pan
Abstract:
In this paper we report an experiment that verifies an atomic-ensemble quantum memory via a measurement-device-independent scheme. A single photon generated via Rydberg blockade in one atomic ensemble is stored in another atomic ensemble via electromagnetically induced transparency. After storage for a long duration, this photon is retrieved and interfered with a second photon to perform joint Bel…
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In this paper we report an experiment that verifies an atomic-ensemble quantum memory via a measurement-device-independent scheme. A single photon generated via Rydberg blockade in one atomic ensemble is stored in another atomic ensemble via electromagnetically induced transparency. After storage for a long duration, this photon is retrieved and interfered with a second photon to perform joint Bell-state measurement (BSM). Quantum state for each photon is chosen based on a quantum random number generator respectively in each run. By evaluating correlations between the random states and BSM results, we certify that our memory is genuinely entanglement-preserving.
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Submitted 29 April, 2021;
originally announced April 2021.
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Field demonstration of distributed quantum sensing without post-selection
Authors:
Si-Ran Zhao,
Yu-Zhe Zhang,
Wen-Zhao Liu,
Jian-Yu Guan,
Weijun Zhang,
Cheng-Long Li,
Bing Bai,
Ming-Han Li,
Yang Liu,
Lixing You,
Jun Zhang,
Jingyun Fan,
Feihu Xu,
Qiang Zhang,
Jian-Wei Pan
Abstract:
Distributed quantum sensing can provide quantum-enhanced sensitivity beyond the shot-noise limit (SNL) for sensing spatially distributed parameters. To date, distributed quantum sensing experiments have been mostly accomplished in laboratory environments without a real space separation for the sensors. In addition, the post-selection is normally assumed to demonstrate the sensitivity advantage ove…
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Distributed quantum sensing can provide quantum-enhanced sensitivity beyond the shot-noise limit (SNL) for sensing spatially distributed parameters. To date, distributed quantum sensing experiments have been mostly accomplished in laboratory environments without a real space separation for the sensors. In addition, the post-selection is normally assumed to demonstrate the sensitivity advantage over the SNL. Here, we demonstrate distributed quantum sensing in field and show the unconditional violation (without post-selection) of SNL up to 0.916 dB for the field distance of 240 m. The achievement is based on a loophole free Bell test setup with entangled photon pairs at the averaged heralding efficiency of 73.88%. Moreover, to test quantum sensing in real life, we demonstrate the experiment for long distances (with 10-km fiber) together with the sensing of a completely random and unknown parameter. The results represent an important step towards a practical quantum sensing network for widespread applications.
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Submitted 5 November, 2020;
originally announced November 2020.
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Device-independent randomness expansion against quantum side information
Authors:
Wen-Zhao Liu,
Ming-Han Li,
Sammy Ragy,
Si-Ran Zhao,
Bing Bai,
Yang Liu,
Peter J. Brown,
Jun Zhang,
Roger Colbeck,
Jingyun Fan,
Qiang Zhang,
Jian-Wei Pan
Abstract:
The ability to produce random numbers that are unknown to any outside party is crucial for many applications. Device-independent randomness generation does not require trusted devices and therefore provides strong guarantees of the security of the output, but it comes at the price of requiring the violation of a Bell inequality for implementation. A further challenge is to make the bounds in the s…
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The ability to produce random numbers that are unknown to any outside party is crucial for many applications. Device-independent randomness generation does not require trusted devices and therefore provides strong guarantees of the security of the output, but it comes at the price of requiring the violation of a Bell inequality for implementation. A further challenge is to make the bounds in the security proofs tight enough to allow randomness expansion with contemporary technology. Although randomness has been generated in recent experiments, the amount of randomness consumed in doing so has been too high to certify expansion based on existing theory. Here we present an experiment that demonstrates device-independent randomness expansion. By developing a Bell test setup with a single-photon detection efficiency of around $84\%$ and by using a spot-checking protocol, we achieve a net gain of $2.57\times10^8$ certified bits with a soundness error $3.09\times10^{-12}$. The experiment ran for $19.2$ h, which corresponds to an average rate of randomness generation of $13,527$ bits per second. By developing the entropy accumulation theorem, we establish security against quantum adversaries. We anticipate that this work will lead to further improvements that push device-independence towards commercial viability.
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Submitted 12 October, 2021; v1 submitted 23 December, 2019;
originally announced December 2019.
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Experimental Realization of Device-Independent Quantum Randomness Expansion
Authors:
Ming-Han Li,
Xingjian Zhang,
Wen-Zhao Liu,
Si-Ran Zhao,
Bing Bai,
Yang Liu,
Qi Zhao,
Yuxiang Peng,
Jun Zhang,
Yanbao Zhang,
William J. Munro,
Xiongfeng Ma,
Qiang Zhang,
Jingyun Fan,
Jian-Wei Pan
Abstract:
Randomness expansion where one generates a longer sequence of random numbers from a short one is viable in quantum mechanics but not allowed classically. Device-independent quantum randomness expansion provides a randomness resource of the highest security level. Here, we report the first experimental realization of device-independent quantum randomness expansion secure against quantum side inform…
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Randomness expansion where one generates a longer sequence of random numbers from a short one is viable in quantum mechanics but not allowed classically. Device-independent quantum randomness expansion provides a randomness resource of the highest security level. Here, we report the first experimental realization of device-independent quantum randomness expansion secure against quantum side information established through quantum probability estimation. We generate $5.47\times10^8$ quantum-proof random bits while consuming $4.39\times10^8$ bits of entropy, expanding our store of randomness by $1.08\times10^8$ bits at a latency of about $13.1$ h, with a total soundness error $4.6\times10^{-10}$. Device-independent quantum randomness expansion not only enriches our understanding of randomness but also sets a solid base to bring quantum-certifiable random bits into realistic applications.
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Submitted 15 February, 2021; v1 submitted 20 February, 2019;
originally announced February 2019.
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Testing Local Realism into the Past without Detection and Locality Loopholes
Authors:
Ming-Han Li,
Cheng Wu,
Yanbao Zhang,
Wen-Zhao Liu,
Bing Bai,
Yang Liu,
Weijun Zhang,
Qi Zhao,
Hao Li,
Zhen Wang,
Lixing You,
W. J. Munro,
Juan Yin,
Jun Zhang,
Cheng-Zhi Peng,
Xiongfeng Ma,
Qiang Zhang,
Jingyun Fan,
Jian-Wei Pan
Abstract:
Inspired by the recent remarkable progress in the experimental test of local realism, we report here such a test that achieves an efficiency greater than (78%)^2 for entangled photon pairs separated by 183 m. Further utilizing the randomness in cosmic photons from pairs of stars on the opposite sides of the sky for the measurement setting choices, we not only close the locality and detection looph…
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Inspired by the recent remarkable progress in the experimental test of local realism, we report here such a test that achieves an efficiency greater than (78%)^2 for entangled photon pairs separated by 183 m. Further utilizing the randomness in cosmic photons from pairs of stars on the opposite sides of the sky for the measurement setting choices, we not only close the locality and detection loopholes simultaneously, but also test the null hypothesis against local hidden variable mechanisms for events that took place 11 years ago (13 orders of magnitude longer than previous experiments). After considering the bias in measurement setting choices, we obtain an upper bound on the p value of 7.87 * 10^-4, which clearly indicates the rejection with high confidence of potential local hidden variable models. One may further push the time constraint on local hidden variable mechanisms deep into the cosmic history by taking advantage of the randomness in photon emissions from quasars with large aperture telescopes.
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Submitted 23 August, 2018;
originally announced August 2018.
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Device independent quantum random number generation
Authors:
Yang Liu,
Qi Zhao,
Ming-Han Li,
Jian-Yu Guan,
Yanbao Zhang,
Bing Bai,
Weijun Zhang,
Wen-Zhao Liu,
Cheng Wu,
Xiao Yuan,
Hao Li,
W. J. Munro,
Zhen Wang,
Lixing You,
Jun Zhang,
Xiongfeng Ma,
Jingyun Fan,
Qiang Zhang,
Jian-Wei Pan
Abstract:
Randomness is critical for many information processing applications, including numerical modeling and cryptography. Device-independent quantum random number generation (DIQRNG) based on the loophole free violation of Bell inequality produces unpredictable genuine randomness without any device assumption and is therefore an ultimate goal in the field of quantum information science. However, due to…
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Randomness is critical for many information processing applications, including numerical modeling and cryptography. Device-independent quantum random number generation (DIQRNG) based on the loophole free violation of Bell inequality produces unpredictable genuine randomness without any device assumption and is therefore an ultimate goal in the field of quantum information science. However, due to formidable technical challenges, there were very few reported experimental studies of DIQRNG, which were vulnerable to the adversaries. Here we present a fully functional DIQRNG against the most general quantum adversaries. We construct a robust experimental platform that realizes Bell inequality violation with entangled photons with detection and locality loopholes closed simultaneously. This platform enables a continuous recording of a large volume of data sufficient for security analysis against the general quantum side information and without assuming independent and identical distribution. Lastly, by developing a large Toeplitz matrix (137.90 Gb $\times$ 62.469 Mb) hashing technique, we demonstrate that this DIQRNG generates $6.2469\times 10^7$ quantum-certified random bits in 96 hours (or 181 bits/s) with uniformity within $10^{-5}$. We anticipate this DIQRNG may have profound impact on the research of quantum randomness and information-secured applications.
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Submitted 27 July, 2018; v1 submitted 24 July, 2018;
originally announced July 2018.
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Experimental demonstration of nonbilocality with truly independent sources and strict locality constraints
Authors:
Qi-Chao Sun,
Yang-Fan Jiang,
Bing Bai,
Weijun Zhang,
Hao Li,
Xiao Jiang,
Jun Zhang,
Lixing You,
Xianfeng Chen,
Zhen Wang,
Qiang Zhang,
Jingyun Fan,
Jian-Wei Pan
Abstract:
Entanglement swapping entangles two particles that have never interacted[1], which implicitly assumes that each particle carries an independent local hidden variable, i.e., the presence of bilocality[2]. Previous experimental studies of bilocal hidden variable models did not fulfill the central requirement that the assumed two local hidden variable models must be mutually independent and hence the…
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Entanglement swapping entangles two particles that have never interacted[1], which implicitly assumes that each particle carries an independent local hidden variable, i.e., the presence of bilocality[2]. Previous experimental studies of bilocal hidden variable models did not fulfill the central requirement that the assumed two local hidden variable models must be mutually independent and hence their conclusions are flawed on the rejection of local realism[3-5]. By harnessing the laser phase randomization[6] rising from the spontaneous emission to the stimulated emission to ensure the independence between entangled photon-pairs created at separate sources and separating relevant events spacelike to satisfy the no-signaling condition, for the first time, we simultaneously close the loopholes of independent source, locality and measurement independence in an entanglement swapping experiment in a network. We measure a bilocal parameter of 1.181$\pm$0.004 and the CHSH game value of 2.652$\pm$0.059, indicating the rejection of bilocal hidden variable models by 45 standard deviations and local hidden variable models by 11 standard deviations. We hence rule out local realism and justify the presence of quantum nonlocality in our network experiment. Our experimental realization constitutes a fundamental block for a large quantum network. Furthermore, we anticipate that it may stimulate novel information processing applications[7,8].
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Submitted 11 December, 2018; v1 submitted 14 July, 2018;
originally announced July 2018.
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A loophole-free Wheeler-delayed-choice experiment
Authors:
H. -L. Huang,
Y. -H. Luo,
B. Bai,
Y. -H. Deng,
H. Wang,
H. -S. Zhong,
Y. -Q. Nie,
W. -H. Jiang,
X. -L. Wang,
J. Zhang,
Li Li,
Nai-Le Liu,
Tim Byrnes,
J. P. Dowling,
Chao-Yang Lu,
Jian-Wei Pan
Abstract:
Wheeler's delayed-choice experiment investigates the indeterminacy of wave-particle duality and the role played by the measurement apparatus in quantum theory. Due to the inconsistency with classical physics, it has been generally believed that it is not possible to reproduce the delayed-choice experiment using a hidden variable theory. Recently, it was shown that this assumption was incorrect, an…
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Wheeler's delayed-choice experiment investigates the indeterminacy of wave-particle duality and the role played by the measurement apparatus in quantum theory. Due to the inconsistency with classical physics, it has been generally believed that it is not possible to reproduce the delayed-choice experiment using a hidden variable theory. Recently, it was shown that this assumption was incorrect, and in fact Wheeler's delayed-choice experiment can be explained by a causal two dimensional hidden-variable theory [R. Chaves, G. B. Lemos, and J. Pienaar, Phys. Rev. Lett. 120, 190401 (2018)]. Here, we carry out an experiment of a device-independent delayed-choice experiment using photon states that are space-like separated, and demonstrate a loophole-free version of the delayed-choice protocol that is consistent with quantum theory but inconsistent with any causal two-dimensional hidden variable theory. This salvages Wheeler's thought experiment and shows that causality can be used to test quantum theory in a complementary way to the Bell and Leggett-Garg tests.
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Submitted 31 May, 2018;
originally announced June 2018.
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Two-photon superbunching of pseudothermal light in a Hanbury Brown-Twiss interferometer
Authors:
Bin Bai,
Jianbin Liu,
Yu Zhou,
Huaibin Zheng,
Hui Chen,
Songlin Zhang,
Yuchen He,
Fuli Li,
Zhuo Xu
Abstract:
Two-photon superbunching of pseudothermal light is observed with single-mode continuous-wave laser light in a linear optical system. By adding more two-photon paths via three rotating ground glasses,g(2)(0) = 7.10 is experimentally observed. The second-order temporal coherence function of superbunching pseudothermal light is theoretically and experimentally studied in detail. It is predicted that…
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Two-photon superbunching of pseudothermal light is observed with single-mode continuous-wave laser light in a linear optical system. By adding more two-photon paths via three rotating ground glasses,g(2)(0) = 7.10 is experimentally observed. The second-order temporal coherence function of superbunching pseudothermal light is theoretically and experimentally studied in detail. It is predicted that the degree of coherence of light can be increased dramatically by adding more multi-photon paths. For instance, the degree of the second- and third-order coherence of the superbunching pseudothermal light with five rotating ground glasses can reach 32 and 7776, respectively. The results are helpful to understand the physics of superbunching and to improve the visibility of thermal light ghost imaging.
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Submitted 10 May, 2017;
originally announced May 2017.
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Superbunching pseudothermal light
Authors:
Yu Zhou,
Bin Bai,
Huaibin Zheng,
Hui Chen,
Jianbin Liu,
Fu-li Li,
Zhuo Xu
Abstract:
A novel and simple superbunching pseudothermal light source is introduced based on common instruments such as laser, lens, pinhole and groundglass. $g^{(2)}(0)=3.66 \pm 0.02$ is observed in the suggested scheme by employing two rotating groundglass. Quantum and classical theories are employed to interpret the observed superbunching effect. It is predicted that $g^{(2)}(0)$ can reach $2^N$ if $N$ r…
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A novel and simple superbunching pseudothermal light source is introduced based on common instruments such as laser, lens, pinhole and groundglass. $g^{(2)}(0)=3.66 \pm 0.02$ is observed in the suggested scheme by employing two rotating groundglass. Quantum and classical theories are employed to interpret the observed superbunching effect. It is predicted that $g^{(2)}(0)$ can reach $2^N$ if $N$ rotating groundglass were employed. These results are helpful to understand the physics of superbunching. The proposed superbunching pseudothermal light may serve as a new type of light to study the second- and higher-order coherence of light and have potential application in improving the visibility of thermal light ghost imaging.
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Submitted 28 February, 2017;
originally announced February 2017.
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Random number generation with cosmic photons
Authors:
Cheng Wu,
Bing Bai,
Yang Liu,
Xiaoming Zhang,
Meng Yang,
Yuan Cao,
Jianfeng Wang,
Shaohua Zhang,
Hongyan Zhou,
Xiheng Shi,
Xiongfeng Ma,
Ji-Gang Ren,
Jun Zhang,
Cheng-Zhi Peng,
Jingyun Fan,
Qiang Zhang,
Jian-Wei Pan
Abstract:
Random numbers are indispensable for a variety of applications ranging from testing physics foundation to information encryption. In particular, nonlocality tests provide a strong evidence to our current understanding of nature -- quantum mechanics. All the random number generators (RNG) used for the existing tests are constructed locally, making the test results vulnerable to the freedom-of-choic…
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Random numbers are indispensable for a variety of applications ranging from testing physics foundation to information encryption. In particular, nonlocality tests provide a strong evidence to our current understanding of nature -- quantum mechanics. All the random number generators (RNG) used for the existing tests are constructed locally, making the test results vulnerable to the freedom-of-choice loophole. We report an experimental realization of RNGs based on the arrival time of cosmic photons. The measurement outcomes (raw data) pass the standard NIST statistical test suite. We present a realistic design to employ these RNGs in a Bell test experiment, which addresses the freedom-of-choice loophole.
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Submitted 23 March, 2017; v1 submitted 21 November, 2016;
originally announced November 2016.
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Design considerations of high-performance InGaAs/InP single-photon avalanche diodes for quantum key distribution
Authors:
Jian Ma,
Bing Bai,
Liu-Jun Wang,
Cun-Zhu Tong,
Ge Jin,
Jun Zhang,
Jian-Wei Pan
Abstract:
InGaAs/InP single-photon avalanche diodes (SPADs) are widely used in practical applications requiring near-infrared photon counting such as quantum key distribution (QKD). Photon detection efficiency and dark count rate are the intrinsic parameters of InGaAs/InP SPADs, due to the fact that their performances cannot be improved using different quenching electronics given the same operation conditio…
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InGaAs/InP single-photon avalanche diodes (SPADs) are widely used in practical applications requiring near-infrared photon counting such as quantum key distribution (QKD). Photon detection efficiency and dark count rate are the intrinsic parameters of InGaAs/InP SPADs, due to the fact that their performances cannot be improved using different quenching electronics given the same operation conditions. After modeling these parameters and developing a simulation platform for InGaAs/InP SPADs, we investigate the semiconductor structure design and optimization. The parameters of photon detection efficiency and dark count rate highly depend on the variables of absorption layer thickness, multiplication layer thickness, excess bias voltage and temperature. By evaluating the decoy-state QKD performance, the variables for SPAD design and operation can be globally optimized. Such optimization from the perspective of specific applications can provide an effective approach to design high-performance InGaAs/InP SPADs.
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Submitted 22 August, 2016;
originally announced August 2016.
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The second-order interference of two independent single-mode He-Ne lasers
Authors:
Jianbin Liu,
Minglan Le,
Bin Bai,
Wentao Wang,
Hui Chen,
Yu Zhou,
Fu-Li Li,
Zhuo Xu
Abstract:
The second-order spatial and temporal interference patterns with two independent single-mode He-Ne lasers are observed in a Hong-Ou-Mandel interferometer. Two-photon interference in Feynman's path integral theory is employed to interpret the experimental results. The conditions to observe the second-order interference pattern with two independent single-mode continuous wave lasers are discussed. I…
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The second-order spatial and temporal interference patterns with two independent single-mode He-Ne lasers are observed in a Hong-Ou-Mandel interferometer. Two-photon interference in Feynman's path integral theory is employed to interpret the experimental results. The conditions to observe the second-order interference pattern with two independent single-mode continuous wave lasers are discussed. It is concluded that two-photon interference exists for not only identical photons, but also photons with different spectrums if the detection system can not distinguish them in principle. The second-order temporal beating with two independent lasers can be employed to measure the coherence time and frequency of one laser if the properties of the other laser were known.
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Submitted 8 October, 2014;
originally announced October 2014.
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Enhanced Feedback Iterative Decoding of Sparse Quantum Codes
Authors:
Yun-Jiang Wang,
Barry C. Sanders,
Bao-Ming Bai,
Xin-Mei Wang
Abstract:
Decoding sparse quantum codes can be accomplished by syndrome-based decoding using a belief propagation (BP) algorithm.We significantly improve this decoding scheme by developing a new feedback adjustment strategy for the standard BP algorithm. In our feedback procedure, we exploit much of the information from stabilizers, not just the syndrome but also the values of the frustrated checks on indiv…
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Decoding sparse quantum codes can be accomplished by syndrome-based decoding using a belief propagation (BP) algorithm.We significantly improve this decoding scheme by developing a new feedback adjustment strategy for the standard BP algorithm. In our feedback procedure, we exploit much of the information from stabilizers, not just the syndrome but also the values of the frustrated checks on individual qubits of the code and the channel model. Furthermore we show that our decoding algorithm is superior to belief propagation algorithms using only the syndrome in the feedback procedure for all cases of the depolarizing channel. Our algorithm does not increase the measurement overhead compared to the previous method, as the extra information comes for free from the requisite stabilizer measurements.
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Submitted 23 November, 2011; v1 submitted 22 December, 2009;
originally announced December 2009.