Coherent Generation of Nonclassical Light on Chip via Detuned Photon Blockade

Abstract

The on-chip generation of nonclassical states of light is a key requirement for future optical quantum hardware. In solid-state cavity quantum electrodynamics, such nonclassical light can be generated from self-assembled quantum dots strongly coupled to photonic crystal cavities. Their anharmonic strong lightmatter interaction results in large optical nonlinearities at the single photon level, where the admission of a single photon into the cavity may enhance (photon tunneling) or diminish (photon blockade) the probability for a second photon to enter the cavity. Here, we demonstrate that detuning the cavity and quantum-dot resonances enables the generation of high-purity nonclassical light from strongly coupled systems. For specific detunings we show that not only the purity but also the efficiency of single-photon generation increases significantly, making high-quality single-photon generation by photon blockade possible with current state-of-the-art samples. [7] or epitaxially grown photonic nanowires [8] for enhanced light off-chip extraction efficiency. On the other hand, photonic crystal cavities provide a promising on-chip route toward optoelectronic integration of QDs due to the established set of associated integrated waveguide and detector structures [9,10]. Such structures will be able to exploit strong light-matter coupling with QDs for the generation of a variety of on-chip nonclassical light states by various quantum-electrodynamical (QED) methods, and recent exotic proposals have even explored the possibility of releasing energy exclusively in bundles of n photons [11]. The phenomena of photon tunneling and photon blockade in strongly coupled systems have been experimentally demonstrated both for the case of the QD on resonance [12][13][14] and near resonance [15] with the cavity (and likewise, only for resonant atom-cavity system [16]). However, in the case of large detuning these effects have only been investigated theoretically [17].In this Letter, we demonstrate the feasibility of performing photon blockade at significant detuning, and indeed the importance of doing so for high-purity and highefficiency operation. We show that by detuning the QD and cavity resonances while operating in the photonblockade regime, the second-order autocorrelation function [g ð2Þ ð0Þ] of the light transmitted through the cavity decreases from g ð2Þ ð0Þ ¼ 0.9 AE 0.05 to g ð2Þ ð0Þ ¼ 0.29 AE 0.04. Simulations of the second-and third-order autocorrelation functions for our system are in excellent agreement with the measurements, and they reveal that not only does the quality of the single photon stream increase, but that the absolute probability of obtaining a single photon increases by a factor of ∼2. Furthermore, we show that the values we obtain for g ð2Þ ð0Þ are only limited by the system parameters (QD-cavity field coupling strength g and cavity field decay rate κ), and that high-quality single-photon emission is within reach for current state-of-the-art samples for specific cavity and QD detunings.The sample i...

Photon blockade in two-emitter-cavity systems

“…2b), and its quality improves for higher detuned emitter-like peaks. This is consistent with the findings in single-emitter CQED systems where the photon blockade at the polariton peak frequency strengthens with the emitter-cavity detuning [3]. We identify a novel effect of reduced second order coherence value at the frequency of the subradiant peakthe subradiant photon blockade (yellow arrows in Fig.…”

“…The photon blockade (PB) effect prevents the absorption of the second photon at specific frequencies due to the nonlinearity of the emitter that dresses the energy states and leads to an anharmonic ladder. This effect has been extensively studied in single-emitter (N = 1) atomic [1, 2] and quantum dot [3,4] cavity quantum electrodynamics (CQED), as well as in circuit QED systems [5]. Here, the effect occurs at the frequencies of the dressed states so-called polaritons (polaritonic PB) and results in a faster emission rate of single photons compared to the bare emitter.…”

Observation of the Unconventional Photon Blockade

“…In the strong coupling regime, where the coupling between the two-level system and the cavity is larger than the cavity decay rate ðg > κÞ [4], photon blockade has been demonstrated in atomic systems [5], quantum dots in photonic crystal cavities [6], and circuit QED [7,8]. At the onset of the weak coupling regime (g ≈ κ), it has been shown that by detuning the dipole transition frequency with respect to the cavity resonance, photon blockade can still be observed [9]. However, moving further into the weak coupling regime (g < κ), which is much easier to achieve [10,11] (in particular if one aims for a small polarization mode splitting), the conventional photon blockade is no longer possible because the energy gap between the polariton states vanishes.…”

Strong photon blockade with intracavity electromagnetically induced transparency in a blockaded Rydberg ensemble

“…The photon blockade has been theoretically and experimentally researched in a variety of systems, such as cavity quantum electrodynamics [1][2][3][4][5][6][7][8][9]. However, experimental realization of strong photon blockade is still a challenging pursuit, because the observation of strong photon blockade requires large nonlinearities with respect to the decay rate of the system.…”