An efficient, tunable, and robust source of narrow-band photon pairs at the ⁸⁷Rb D1 line

Abstract

We present an efficient, bright, and robust source of photons at the rubidium D1-line (795 nm) with a narrow bandwidth of δ = 226(1) MHz. The source is based on non-degenerate, cavity-enhanced spontaneous parametric down-conversion in a monolithic optical parametric oscillator far below threshold. The setup allows for efficient coupling to single mode fibers. A heralding efficiency of η heralded = 45(5) % is achieved, and the uncorrected number of detected photon pairs is 3.8×10 3 cts/(s mW). For pair generation rates up to 0.5 MHz, the source emits heralded single photons with negligible contamination from higher photon number states as evidenced by g(2) c < 0.01. The source is intrinsically stable due to the monolithic configuration. Frequency drifts are on the order of δ /20 per hour even without active stabilization. By applying mechanical strain, the source frequency can be fine-tuned within a range of ≥ 2 GHz.

Bright multiplexed source of indistinguishable single photons with tunable GHz-bandwidth at room temperature

“…This work Hot vapor 55* 254* [41] Hot vapor 1 42 [8] Cavity SPDC 6 200** [41] Hot vapor 1 42 [9] Cavity SPDC 0.11 11 [10] Cavity SPDC 2.5 11.25 [7] Cavity SPDC 6.1 92** [5] Cavity SPDC 0.045 60 [36] Hot vapor 30 84 [45] FWM in MRR 26 360** [39] Hot vapor 12 360 [33] Hot vapor 30 126 [35] Hot vapor 40 6 [40] Hot vapor 8 97 [29] Cold atoms 0.031 5800 [4] Cavity SPDC 8 65 [6] Cavity SPDC 2.9 40 [44] FWM in MRR 20 600** [43] FWM in MRR 20 100** [28] Cold atoms 0.36 20 [11] Cavity SPDC 2.5 50 [12] Cavity SPDC 42.5 600** * One representative point from the curve shown in Fig. 1 of the main text.…”

“…However, the photons generated in SPDC are inherently broadband, and thus it is difficult to interface them with atomic ensembles, as required for many quantum communication and computation protocols. Narrowing the source bandwidth by placing the nonlinear crystals inside an optical cavity generally comes at the cost of a reduction in other performance parameters and in technical overhead [3][4][5][6][7][8][9][10][11][12].…”

“…R is the actual detection rate in kilo-counts per second (kcps). Sources: Hot vapor [33,35,36,[39][40][41], cold atoms [28,29], cavity SPDC [4][5][6][7][8][9][10][11][12], FWM in MRR (Microring resonators) [43][44][45]. See Supplementary Material for more details.…”

Single-mode Quantum Non-Gaussian Light from Warm Atoms

“…A conventional enhancement of modeness in these systems corresponds to a severe filtration resulting in a small two-photon coupling efficiencies accompanied by a high susceptibility of observability of QNG to residual noise. Despite significant advancements in demonstrations of operation of narrowband SPDC sources utilizing optical cavities have been demonstrated [36][37][38][39][40][41][42], with most recent works approaching a single-mode regime [43], a provable observation of a single-mode QNG light still remains an open challenge [3]. A rapid development in realization of spon-taneous four-wave mixing (SFWM) photon sources with warm atomic vapors over the past decade brought experimentally very feasible demonstrations of a rich variety of spectrally narrow-band and provably nonclassical light with strongly sub-Poissonian and anti-bunched statistics promising a natural applicability for interaction with target atomic ensembles and storage in quantum memories due to their spectral compatibility [44][45][46][47][48][49][50][51][52][53][54].…”

High nonclassical correlations of large-bandwidth photon pairs generated in warm atomic vapor

“…The large demand for nonclassical light with spectral bandwidth comparable to typical linewidths of atomic optical dipole transition motivated by theoretical proposals for scalable long distance quantum communication [7,8] stimulated the intensive development of photon sources based on the excitation of optical nonlinear processes in cold atomic ensembles [9][10][11][12][13][14]. More recently, demonstrations of nonclassically correlated photon sources in the frequency bandwidth regimes corresponding to tens of MHz based on the process of PDC in optical cavities have been reported [15][16][17][18][19][20][21].…”