Surface acoustic wave regulated single photon emission from a coupled quantum dot–nanocavity system

Abstract

A coupled quantum dot-nanocavity system in the weak coupling regime of cavityquantumelectrodynamics is dynamically tuned in and out of resonance by the coherent elastic field of a fSAW 800 MHz surface acoustic wave. When the system is brought to resonance by the sound wave, light-matter interaction is strongly increased by the Purcell effect. This leads to a precisely timed single photon emission as confirmed by the second order photon correlation function, g (2) . All relevant frequencies of our experiment are faithfully identified in the Fourier transform of g (2) , demonstrating high fidelity regulation of the stream of single photons emitted by the system. Solid state cavity-quantumelectrodynamics (cQED) systems formed by an exciton confined in a single semiconductor quantum dot (QD) and strongly localized optical modes in a photonic nanocavity (PhNCs) have been intensely studied over the past years [1,2]. Membranes patterned with two-dimensional photonic crystals represent a particularly attractive platform for the integration of large scale photonic networks on a chip [3]. In this architecture, both the weak[4] and strong coupling regime [5,6] of cQED have been demonstrated. These key achievements paved the way towards efficient sources of single photons [7,8] or optical switching operations controlled by single photons [9]. So far, the dynamic control of the spontaneous emission [10] or the coherent evolution of the coupled QD-PhNC cQED system [11,12] has relied mainly on all-optical approaches, although all-electrical approaches would be highly desirable for real-world applications due to their reduced level of complexity. However, to switch an electric field and induce a Stark effect [13] with sufficent bandwidth, nanoscale electric contacts are required [14]. In addition to light, these membrane structures guide [15] or confine vibronic excitations with strong optomechanical coupling strength [16,17]. These phononic modes can be directly employed to interface photonic crystal membranes by radio frequency surface acoustic waves (SAWs) [18,19]. As SAWs can be excited at GHz frequencies on piezoelectric materials [20,21], electrically induced and acoustically driven quantum gates are well within reach on this platform [22]. Moreover, SAWs have a long-standing tradition to control optically active semiconductors [23]. On one hand, acoustic charge transport [24] in piezoelectric semiconductors by these phononic modes have been proposed [25] and demonstrated [26][27][28] to regulate the carrier injection into QDs for precisely triggered single photon sources. On the other hand, the dynamic strain accompanying the SAW dynamically tunes optical modes in optical cavities [18,29] or excitons in QDs [30,31]. Here we demonstrate the dynamic, acousto-optic control of a prototypical QD-PhNC system by a f SAW 800 MHz SAW. We show that the acoustic field precisely modulates the energy detuning between the QD and PhNC on sub-nanosecond timescales switching the emission rate of the QD by a factor of 4. The photon statis...

Surface acoustic wave modulation of a coherently driven quantum dot in a pillar microcavity

“…Most reports on * bruno.villa@crl.toshiba.co.uk † Present address: Department of Electronic & Electrical Engineering, University of Sheffield, Mappin Street, Sheffield S1 3JD, United Kingdom SAW-modulated quantum structures to date are limited to samples without Purcell effect [20][21][22]. Although there is a recent report of SAW-modulated emission from a photonic crystal cavity [23], a hybrid platform combining SAWs and pillar microcavities has clear advantages and is yet to be investigated. Here, we show that it is possible to modulate the energy levels of a QD inside a pillar microcavity with a SAW.…”

Single-photon emission from single-electron transport in a SAW-driven lateral light-emitting diode

“…However, to the authors' knowledge, no evidence for photon antibunching or single-photon emission has been observed. Note that a few works based on SAW-injected or SAW-regulated excitons in a QD have shown singlephoton emission [43][44][45]. However, they still rely on the presence of a QD and thus suffer from the randomness issue.…”

Quantum Dot Optomechanics in Suspended Nanophononic Strings

“…Rayleigh SAWs are generated on the unpatterned heterostructure by a signal generator connected to the IDTs. The SAW is generated in short pulses to suppress unwanted heating of the sample . Furthermore, the laser exciting the µ‐PL is synchronized with the electrically generated SAW pulses by a delay generator to probe the QDs only when the acoustic wave is present.…”

“…One of the first applications of SAW envisioned and implemented in QD‐based quantum technologies was the dynamic acoustic pumping and charge state control via the acousto‐electric effect . Moreover, QDs can be integrated in fully suspended photonic crystal membranes with SAW‐tunable circuit elements enabling the dynamic control of light–matter interactions at gigahertz frequencies . Such suspended systems confine both photons and phonons in the plane .…”

“…Best fits of Equation (full lines in Figure b,c) faithfully reproduce the experimental data and allow us to quantify to be 0.23 and 1.40 meV for the Rayleigh SAW and on the nanophononic string, respectively. The minute offset of the center of the modulated relative to the unmodulated emission line arises most likely due to heating despite of the employed pulsed SAW excitation scheme . In the Supporting Information we present stroboscopic experiments in Figure S1, Supporting Information.…”