Towards optimal single-photon sources from polarized microcavities

Abstract

An optimal single-photon source should deterministically deliver one and only one photon at a time, with no trade-off between the source's efficiency and the photon indistinguishability. However, all reported solid-state sources of indistinguishable single photons had to rely on polarization filtering which reduced the efficiency by 50%, which fundamentally limited the scaling of photonic quantum technologies. Here, we overcome this final long-standing challenge by coherently driving quantum dots deterministically coupled to polarization-selective Purcell microcavities-two examples are narrowband, elliptical micropillars and broadband, elliptical Bragg gratings. A polarization-orthogonal excitation-collection scheme is designed to minimize the polarization-filtering loss under resonant excitation. We demonstrate a polarized single-photon efficiency of 0.60(2), a single-photon purity of 0.991(3), and an indistinguishability of 0.973(5). Our work provides promising solutions for truly optimal single-photon sources combining near-unity indistinguishability and near-unity system efficiency simultaneously.Single photons are appealing candidates for quantum communications 1,2 , quantumenhanced metrology 3,4 and quantum computing 5,6 . In view of the quantum information applications, the single photons are required to be controllably prepared with a high efficiency into a given quantum state. Specifically, the single photons should possess the same polarization, spatial mode, and transform-limited spectro-temporal profile for a high-visibility Hong-Ou-Mandel-type quantum interference 1,7 .Self-assembled quantum dots show so far the highest quantum efficiency among solid-state quantum emitters and thus can potentially serve as an ideal single-photon source 8-15 . There has been encouraging progress in recent years in developing highperformance single-photon sources 11 . Pulsed resonant excitation on single quantum dots has been developed to eliminate dephasing and time jitter, which created single photons with near-unity indistinguishability 15 . Further, by combining the resonant excitation with Purcell-enhanced micropillar 16,17 or photonic crystals 18,19 , the generated transform-limited 20,21 single photons have been efficiently extracted out of the bulk and funneled into a single mode at far field. Despite the recent progress 16-22 , the experimentally achieved polarized-single-photon efficiency (defined as the number of single-polarized photons extracted from the bulk semiconductor and collected by the first lens per pumping pulse) is ~33% in ref. 16 and ~15% in ref. 17, still fell short of the minimally required efficiency of 50% for boson sampling to show computational advantage to classical algorithms 23 , and was below the efficiency threshold of 67% for photon-loss-tolerant encoding in cluster-state models of optical quantum computing 24 . It should be noted that a <50% single-photon efficiency would render nearly all linear optical quantum computing schemes 1,5 not scalable.The indistinguishable single-photon...

Lifetimes and Quantum Efficiencies of Quantum Dots Deterministically Positioned in Photonic‐Crystal Waveguides

“…By positioning the QDs at the mode maximum in the center of the unit cell, we are also able to deterministically fabricate photon‐emitter interfaces with near‐unity coupling efficiencies. These capabilities are critical to the large‐scale fabrication of optimal single photon [ 43,44 ] and entangled photon [ 3 ] sources, respectively, and the creation of complex quantum photonic circuits, [ 45,46 ] as deterministic positioning is a key method for controllably scaling up nanophotonic systems and hence enable the coupling of multiple QDs.…”

Orthogonally Polarized Luminescence of Single Bismuth Phosphate Microcrystal Doped with Europium

“…The polarized features of photons are of great importance for variety of lighting applications. Especially, the linearly and/or orthogonally polarized light is desirable for use in laser, display, bioimaging, precision sensing and metrology, quantum communication, and computing, [1][2][3][4][5][6][7][8][9] and numerous applications are related to the fact that single micro/nanosized emitters can generate light with independently predesigned polarization features. To date, the polarized luminescence behaviors have been widely explored in low-dimensional semiconductor exhibit good crystallinity.…”

Simulating the dynamics of single photons in boson sampling devices with matrix product states

“…Thus, BosonSampling is considered as a promising candidate to experimentally demonstrate the quantum supremacy in the near future [11]. So far, a number of elegant BosonSampling experiments has been achieved with linear optics on a small scale [12][13][14][15][16][17][18][19][20][21][22]. In addition, BosonSampling can be regarded as a special multiparticle quantum walk, and thus investigating its nonclassical correlations during the quantum dynamics is also an interesting task [23][24][25][26][27][28].…”