Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Nano Letters

Quantum Beat between Sunlight and Single Photons

Z.-C. Duan, Yu-Hao Deng, Ying Yu, Si Chen, Jian Qin, Hui Wang, Xing Ding, Li-Chao Peng, Christian Schneider, Da‐Wei Wang, Sven Höfling, Jonathan P. Dowling, Chao‐Yang Lu, Jian-Wei Pan

Published Dec 16, 2019• 8 citations
Publisher

Abstract

We demonstrate fourth-order quantum beat between sunlight and single photons from a quantum dot. With a fast time-resolved detection system, we observed high-visibility quantum beat between the independent photons of different frequencies from the two astronomically separated light sources. The temporal dynamics of the beat oscillation indicate the coherent behavior of the interfering photons, and the raw visibility of two-photon interference shows violation of the classical limit with a frequency mismatch of three-times the line width.

DOI
10.1021/acs.nanolett.9b03512

Related papers

Time-Resolved Two-Photon Quantum Interference

T. Legero, Tatjana Wilk, A. Kuhn +1 more

Abstract The interference of two independent single-photon pulses impinging on a beam splitter is analysed in a generalised time-resolved manner. Different aspects of the phenomenon are elaborated using different representations of the single-photon wave packets, like the decomposition into single-frequency field modes or spatio-temporal modes matching the photonic wave packets. Both representations lead to equivalent results, and a photon-by-photon analysis reveals that the quantum-mechanical two-photon interference can be interpreted as a classical one-photon interference once a first photon is detected. A novel time-dependent quantum-beat effect is predicted if the interfering photons have different frequencies. The calculation also reveals that full two-photon fringe visibility can be achieved under almost any circumstances by applying a temporal filter to the signal. PACS 42.50.Dv, 42.50.Ct 1

•Jan 1, 2003•113 citations

Temporal interference with frequency-controllable long photons from independent cold atomic sources

Peng Qian, Zhenjie Gu, Rong Wen +2 more

The interference of single photons from independent sources is an essential tool in quantum information processing. However, the interfering of photons with long temporal states in a time-resolved manner has rarely been studied. This is because without transmitting spectral filters or coupling to a cavity mode single photons generated in traditional nonlinear crystals suffer from a short temporal profile below 1 ns. With spectral correlation maintained in the biphotons generated from spontaneous four-wave mixing process in cold atom clouds, here we demonstrate the temporal interference of two frequency-tunable long photons from two independent cold atomic sources. We observe and analyze the interference of frequency-mismatched photons, where the phenomenon of the quantum beat at megahertz separation is displayed. Our paper provides more details for the quantum beat of two independent narrow-band single photons, which may find potential application in frequency-encoded photonic qubits in quantum information processing.

Physical Review A•Jan 4, 2018•5 citations

Quantum Beat of Two Single Photons

Thomas Legero, Tatjana Wilk, Markus Hennrich +2 more

The interference of two single photons impinging on a beam splitter is measured in a time-resolved manner. Using long photons of different frequencies emitted from an atom-cavity system, a quantum beat with a visibility close to 100% is observed in the correlation between the photodetections at the output ports of the beam splitter. The time dependence of the beat amplitude reflects the coherence properties of the photons. Most remarkably, simultaneous photodetections are never observed, so that a temporal filter allows one to obtain perfect two-photon coalescence even for nonperfect photons.

arXiv:quant-ph/0406096•Physical Review Letters•Aug 13, 2004•289 citations

Interference of single photons with ultralong coherence time

Manman Wang, Yanfeng Li, Hanqing Liu +5 more

Two-photon interference (TPI) is a fundamental phenomenon in quantum optics and plays a crucial role in optical quantum technologies. TPI is commonly considered as quantum interference with an upper bound of 100% for both the TPI and the beat visibility in contrast to its classical counterpart with a maximum visibility of 50%. However, this is not always the case. Here, we report a simultaneous observation of quantum and classical TPI of single photons with ultralong coherence time, which is five orders of magnitude longer than the photon correlation time. We observe a TPI visibility of 94.3% ± 0.2% well above the 50% classical limit indicating the quantum feature, and a beat visibility of 50% reflecting the classical feature. In addition an anti-bunching central dip due to single-photon anti-correlation, we also observe two bunching side peaks in cross correlation curves for indistinguishable photons. Using the general wave superposition theory and the quantum field approach, we derive the same cross correlation functions, which fully reproduce and explain the experiments. Our results reveal that the quantum and classical features of TPI result from the same interference, as the fourth-order temporal interference arises from the second-order temporal interference between two photons on the timescale of the photon coherence time.

arXiv:2404.05158•Applied Physics Letters•Oct 7, 2024•5 citations

Quantum Interference between Light Sources Separated by 150 Million Kilometers

Yu-Hao Deng, Hui Wang, Xing Ding +18 more

We report an experiment to test quantum interference, entanglement, and nonlocality using two dissimilar photon sources, the Sun and a semiconductor quantum dot on the Earth, which are separated by ∼150 million kilometers. By making the otherwise vastly distinct photons indistinguishable in all degrees of freedom, we observe time-resolved two-photon quantum interference with a raw visibility of 0.796(17), well above the 0.5 classical limit, providing unambiguous evidence of the quantum nature of thermal light. Further, using the photons with no common history, we demonstrate postselected two-photon entanglement with a state fidelity of 0.826(24) and a violation of Bell inequality by 2.20(6). The experiment can be further extended to a larger scale using photons from distant stars and open a new route to quantum optics experiments at an astronomical scale.

arXiv:1905.02868•Physical Review Letters•Aug 21, 2019•87 citations

Multi-order quantum beating effect of three-photon temporal interference with nondegenerate fluorescence sources

Ruimin Wang, Faizan Raza, Renjun Pang +3 more

The multi-order quantum beating effect of three-photon temporal interference generated by three nondegenerate fluorescence sources is studied. The third-order temporal correlation function of three nondegenerate photons results from the superposition of two-photon and three-photon bunching, multi-order quantum beating and temporal interference of three-photon. The simulate results show strong quantum beating and photon bunching behavior. The visibility of interference pattern, and the switching between photon bunching and beating effect can be modulated by the frequency difference, bandwidth of photons and the relative time delay of detectors. Such controllable coherent signal has potential applications as router and logic gate in quantum communication and information processing.

Results in Physics•Oct 15, 2019•3 citations
We demonstrate fourth-order quantum beat between sunlight and single photons from a quantum dot. With a fast time-resolved detection system, we observed high-visibility quantum beat between the independent photons of different frequencies from the two astronomically separated light sources. The temporal dynamics of the beat oscillation indicate the coherent behavior of the interfering photons, and the raw visibility of two-photon interference shows violation of the classical limit with a frequency mismatch of three-times the line width.
Abstract The interference of two independent single-photon pulses impinging on a beam splitter is analysed in a generalised time-resolved manner. Different aspects of the phenomenon are elaborated using different representations of the single-photon wave packets, like the decomposition into single-frequency field modes or spatio-temporal modes matching the photonic wave packets. Both representations lead to equivalent results, and a photon-by-photon analysis reveals that the quantum-mechanical two-photon interference can be interpreted as a classical one-photon interference once a first photon is detected. A novel time-dependent quantum-beat effect is predicted if the interfering photons have different frequencies. The calculation also reveals that full two-photon fringe visibility can be achieved under almost any circumstances by applying a temporal filter to the signal. PACS 42.50.Dv, 42.50.Ct 1
The interference of single photons from independent sources is an essential tool in quantum information processing. However, the interfering of photons with long temporal states in a time-resolved manner has rarely been studied. This is because without transmitting spectral filters or coupling to a cavity mode single photons generated in traditional nonlinear crystals suffer from a short temporal profile below 1 ns. With spectral correlation maintained in the biphotons generated from spontaneous four-wave mixing process in cold atom clouds, here we demonstrate the temporal interference of two frequency-tunable long photons from two independent cold atomic sources. We observe and analyze the interference of frequency-mismatched photons, where the phenomenon of the quantum beat at megahertz separation is displayed. Our paper provides more details for the quantum beat of two independent narrow-band single photons, which may find potential application in frequency-encoded photonic qubits in quantum information processing.
The interference of two single photons impinging on a beam splitter is measured in a time-resolved manner. Using long photons of different frequencies emitted from an atom-cavity system, a quantum beat with a visibility close to 100% is observed in the correlation between the photodetections at the output ports of the beam splitter. The time dependence of the beat amplitude reflects the coherence properties of the photons. Most remarkably, simultaneous photodetections are never observed, so that a temporal filter allows one to obtain perfect two-photon coalescence even for nonperfect photons.
Two-photon interference (TPI) is a fundamental phenomenon in quantum optics and plays a crucial role in optical quantum technologies. TPI is commonly considered as quantum interference with an upper bound of 100% for both the TPI and the beat visibility in contrast to its classical counterpart with a maximum visibility of 50%. However, this is not always the case. Here, we report a simultaneous observation of quantum and classical TPI of single photons with ultralong coherence time, which is five orders of magnitude longer than the photon correlation time. We observe a TPI visibility of 94.3% ± 0.2% well above the 50% classical limit indicating the quantum feature, and a beat visibility of 50% reflecting the classical feature. In addition an anti-bunching central dip due to single-photon anti-correlation, we also observe two bunching side peaks in cross correlation curves for indistinguishable photons. Using the general wave superposition theory and the quantum field approach, we derive the same cross correlation functions, which fully reproduce and explain the experiments. Our results reveal that the quantum and classical features of TPI result from the same interference, as the fourth-order temporal interference arises from the second-order temporal interference between two photons on the timescale of the photon coherence time.
We report an experiment to test quantum interference, entanglement, and nonlocality using two dissimilar photon sources, the Sun and a semiconductor quantum dot on the Earth, which are separated by ∼150 million kilometers. By making the otherwise vastly distinct photons indistinguishable in all degrees of freedom, we observe time-resolved two-photon quantum interference with a raw visibility of 0.796(17), well above the 0.5 classical limit, providing unambiguous evidence of the quantum nature of thermal light. Further, using the photons with no common history, we demonstrate postselected two-photon entanglement with a state fidelity of 0.826(24) and a violation of Bell inequality by 2.20(6). The experiment can be further extended to a larger scale using photons from distant stars and open a new route to quantum optics experiments at an astronomical scale.
The multi-order quantum beating effect of three-photon temporal interference generated by three nondegenerate fluorescence sources is studied. The third-order temporal correlation function of three nondegenerate photons results from the superposition of two-photon and three-photon bunching, multi-order quantum beating and temporal interference of three-photon. The simulate results show strong quantum beating and photon bunching behavior. The visibility of interference pattern, and the switching between photon bunching and beating effect can be modulated by the frequency difference, bandwidth of photons and the relative time delay of detectors. Such controllable coherent signal has potential applications as router and logic gate in quantum communication and information processing.