Coherently driving a single quantum two-level system with dichromatic laser pulses

Abstract

Efficient excitation of a single two-level system usually requires that the driving field is at the same frequency as the atomic transition. However, the scattered laser light in solid-state implementations can dominate over the single photons, imposing an outstanding challenge to perfect single-photon sources. Here, we propose a background-free method using a phase-locked dichromatic electromagnetic field with no spectral overlap with the optical transition for a coherent control of a twolevel system, and we demonstrate this method experimentally with a single quantum dot embedded in a micropillar. Single photons generated by π excitation show a purity of 0.988(1) and indistinguishability of 0.962(6). Further, the phasecoherent nature of the two-color excitation is captured by the resonancefluorescence intensity dependence on the relative phase between the two pulses.

On-chip deterministic operation of quantum dots in dual-mode waveguides for a plug-and-play single-photon source

“…We measure a raw visibility of V raw = (91 ± 2)%, which, after correcting for the finite g (2) (0) and setup imperfections corresponds to V = (96 ± 2)% (see Supplementary Note 6 for details). The measured indistinguishability is on par with the best reported value with cross-polarized resonant excitation 10 and only superseded by experiments relying on excitation pulse-engineering 35 , 36 .…”

“…The measured indistinguishability is on par with the best reported value with cross-polarized resonant excitation 10 and only superseded by experiments relying on excitation pulse-engineering 35,36 .…”

“…The robust excitation process implies that the device could be operated continuously without any realignment, and as a proof-of-concept we operated the source hands-free for over 110 h with <2% fluctuation in the generation rate ( Supplementary Note 7). The circuit will also enable improving the collection efficiency for more advanced excitation schemes relying on dichromatic laser pulses 36 , which are typically limited by low-efficiency spectral filters. Large Purcell enhancement of the radiative decay rate for overcoming residual decoherence and increasing the source repetition rate can also be achieved through a small modification of the circuit 37 .…”

Elliptical micropillar cavity design for highly efficient polarized emission of single photons

“…For a QD in a bulk material, the large index contrast at the semiconductor-air interface 6 leads to a low collection efficiency, and it is necessary to structure the photonic environment to direct the emitted photons towards the collection optics. 1 The relatively large penetration of light into metals at optical frequencies and the associated loss have motivated the development of two classes of all-dielectric SPS designs; narrow-band designs such as the micro-cavity pillar, [7][8][9][10][11][12][13][14][15][16][17][18] where the light emission is controlled using cavity quantum electrodynamics effects, and broad-band designs including the photonic nanowire, 19,20 the photonic crystal waveguide 21 and the microlens 22 , where the emission is controlled using a combination of dielectric screening, slow-light and classical beam shaping effects.…”

Multiphoton Graph States from a Solid-State Single-Photon Source

“…25,34 Thus, the fidelity of generated states by SPS can approach to one and the upper limit of entangled photons can be greatly extended. These strategies, such as low density and high quality QD wafer growth, better single QD-cavity coupling by optimizing cavity structure, [47][48][49] and proper excitation method [50][51][52][53] will help to approach an ideal SPS. 25 As the number of entangled photons increase, a change in the production rate of the prepared state is another factor for performance, which is related to scalability of system.…”