Shaping the Biphoton Temporal Waveform with Spatial Light Modulation

Zhao, Luwei; Guo, Xianxin; Sun, Yuan; Su, Yumian; Loy, M. M. T.; Du, Shengwang

doi:10.1103/physrevlett.115.193601

Cited by 52 publications

(29 citation statements)

References 32 publications

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“…This is determined by the small optical depth of ∼1 of the atomic vapour cell, which is limited by the maximally allowed temperature (<70 °C) of the paraffin coating. If we can further increase the cell temperature while maintaining a low spin relaxation rate, we expect to improve the heralding efficiency and generate biphotons with richer waveforms by engineering the spatial profile of the pump beam, as those demonstrated in cold atoms 19 .…”

Section: Discussionmentioning

confidence: 99%

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Subnatural-linewidth biphotons from a Doppler-broadened hot atomic vapour cell

Shu¹,

Chen²,

Chow³

et al. 2016

Nat Commun

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104

118

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Entangled photon pairs, termed as biphotons, have been the benchmark tool for experimental quantum optics. The quantum-network protocols based on photon–atom interfaces have stimulated a great demand for single photons with bandwidth comparable to or narrower than the atomic natural linewidth. In the past decade, laser-cooled atoms have often been used for producing such biphotons, but the apparatus is too large and complicated for engineering. Here we report the generation of subnatural-linewidth (<6 MHz) biphotons from a Doppler-broadened (530 MHz) hot atomic vapour cell. We use on-resonance spontaneous four-wave mixing in a hot paraffin-coated 87Rb vapour cell at 63 °C to produce biphotons with controllable bandwidth (1.9–3.2 MHz) and coherence time (47–94 ns). Our backward phase-matching scheme with spatially separated optical pumping is the key to suppress uncorrelated photons from resonance fluorescence. The result may lead towards miniature narrowband biphoton sources.

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Section: Discussionmentioning

confidence: 99%

“…Subnatural-linewidth biphotons with controllable waveforms have been produced from spontaneous four-wave mixing (SFWM) in cold atoms (10–100 μK) assisted with electromagnetically induced transparency (EIT) 15 16 17 18 19 or cavity 20 . However, cold-atom systems require expert knowledge in laser cooling and trapping.…”

mentioning

confidence: 99%

Subnatural-linewidth biphotons from a Doppler-broadened hot atomic vapour cell

Shu¹,

Chen²,

Chow³

et al. 2016

Nat Commun

Self Cite

104

118

View full text Add to dashboard Cite

show abstract

“…Different from the external spectral filtering in the SPDC scheme, the EIT effect governs not only the transmission of the photons but mainly the phase matching condition of the FWM process. The phase matching condition, therefore, is dependent on the atomic ensemble and the coupling field and can be manipulated temporally much more easily [38][39][40][41][42]. In this Letter, we show that the heralded single photon with a coherence time of 100 ns directly heralded from time-frequency entangled biphotons generated from cold atom clouds is in a temporally pure quantum state.…”

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confidence: 99%

Temporal Purity and Quantum Interference of Single Photons from Two Independent Cold Atomic Ensembles

Qian

Cao

et al. 2016

Phys. Rev. Lett.

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The temporal purity of single photons is crucial to the indistinguishability of independent photon sources for the fundamental study of the quantum nature of light and the development of photonic technologies. Currently, the technique for single photons heralded from time-frequency entangled biphotons created in nonlinear crystals does not guarantee the temporal-quantum purity, except using spectral filtering. Nevertheless, an entirely different situation is anticipated for narrow-band biphotons with a coherence time far longer than the time resolution of a single-photon detector. Here we demonstrate temporally pure single photons with a coherence time of 100 ns, directly heralded from the time-frequency entangled biphotons generated by spontaneous four-wave mixing in cold atomic ensembles, without any supplemented filters or cavities. A near-perfect purity and indistinguishability are both verified through Hong-Ou-Mandel quantum interference using single photons from two independent cold atomic ensembles. The time-frequency entanglement provides a route to manipulate the pure temporal state of the single-photon source. DOI: 10.1103/PhysRevLett.117.013602 The purity of the quantum state of a single photon is a prerequisite of its indistinguishability with single photons from other independent sources, and the latter is an essential basis for the realization of a scalable quantum network with distant and independent nodes [1][2][3][4][5]. Furthermore, the temporal purity of a single photon is crucial to the development of photonic technologies for quantum information science [6,7]. The traditional method to produce indistinguishable single photons is heralding time-frequency entangled biphotons generated from spontaneous parametric down-conversion (SPDC) in a nonlinear crystal which is pumped by ultrashort pulses [4,5,8]. In recent decades many new physical systems have been developed [9-13] to obtain pure single photons without time-frequency entanglement built in.In the community of quantum communication, SPDC in χ ð2Þ nonlinear media is still the preferable way to produce entangled biphotons because of its simplicity in the operation and the potential for on-chip integration and scaling up [14][15][16]. However, the intrinsic feasible phase matching condition of SPDC crystal allows an extremely broad range of temporal modes. Therefore, the typical temporal coherence time of the photon source is of femtosecond scale. Compared to the time response of most commercial single-photon detectors, which is about 1 ns, this temporal coherence time is so short that the trigger photon of the heralded single photon is measured with a large time uncertainty. This time uncertainty damages the temporal quantum purity of the single-photon source. To circumvent the time uncertainty problem due to the slowness of the detectors, a common practice is to use external spectral filtering including passive filtering with narrowband filters [4,5,17] and active filtering with an optical cavity [18]. In this case, the temporal state o...

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“…This figure has previously been demonstrated to depend explicitly on the spectral structure of the two-photon state, and that some of its feature can attest the presence of entanglement, although a quantitative estimate has not been obtained 22 . Recent studies have extended the usefulness of this technique for the reconstruction of the spectral wavefunction for the case of cw pumping 23 , 24 . They effectively combine HOM interferometry with spectral shearing, obtained directly by tuning the two-photon source, hence avoiding extra nonlinear components.…”

Section: Introductionmentioning

confidence: 99%