Abstract
Entanglement, describing the inseparability of a quantum multiparty system, is one of the most intriguing features of quantum mechanics. Violation of Bell inequality, for ruling out the possibility of local hidden variable theories, is commonly used as a strong witness for quantum entanglement. In previous Bell test experiments with photonic entanglement based on two-photon coincidence measurement, the photon temporal wave packets are absorbed completely by the detectors. That is, the photon coherence time is much shorter than the detection time window. Here we demonstrate generation of frequency-bin entangled narrowband biphotons, and for the first time, test the Clauser-Horne-Shimony-Holt (CHSH) Bell inequality |S|<= 2 for their nonlocal temporal correlations with time-resolved detection. We obtain a maximum |S| value of 2.52+/-0.48 that violates the CHSH inequality. Our result will have applications in quantum information processing involving time-frequency entanglement.
Highlights
As one of the most important features of quantum mechanics, entanglement is essential in quantum information processing, quantum computation, and quantum communication [1]
The nonlocal correlations between distant entangled photons provide a standard platform for the Bell test [15,16,17] and confirm that quantum mechanics is incompatible with the local hidden-variable theories, which is the essence of the Einstein–Podolsky–Rosen (EPR) paradox [18]
We demonstrate the generation of frequency-bin entangled narrowband biphotons using spontaneous four-wave mixing (SFWM) in cold atoms for testing Bell’s theorem
Summary
As one of the most important features of quantum mechanics, entanglement is essential in quantum information processing, quantum computation, and quantum communication [1]. Time-frequency entanglement has been studied intensively [8,9,10,12,13,14], the nonlocal correlation between the arrival times of frequency-bin entangled photons on the detectors (or the biphoton temporal correlation) has never been used for testing Bell’s theorem. The recent development of narrowband biphoton generation makes it possible to reveal the rich temporal quantum state information directly using time-resolved single-photon counters. We demonstrate the generation of frequency-bin entangled narrowband biphotons using SFWM in cold atoms for testing Bell’s theorem. We test the Clauser–Horne–Shimony–Holt (CHSH) Bell inequality jSj ≤ 2 for their nonlocal temporal correlations with time-resolved detection. Of Bell test, and opens a new way to study the time-frequency entanglement with time-resolved detection
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