Exceptional Photon Blockade: Engineering Photon Blockade with Chiral Exceptional Points

Abstract

Non‐hermitian spectral degeneracies, known as exceptional points (EPs), feature the simultaneous coalescence of both eigenvalues and the associated eigenstates of a system. A host of intriguing EP effects and their applications have been revealed in the classical realm, such as loss‐induced lasing, single‐mode laser, and EP‐enhanced sensing. Here, it is shown that a purely quantum effect, known as single‐photon blockade, emerges in a Kerr microring resonator due to EP‐induced asymmetric coupling between the optical modes and the nonlinearity‐induced anharmonic energy‐level spacing. A striking feature of this photon blockade is that it emerges at two‐photon resonance which in Hermitian systems will only lead to photon‐induced tunneling but not to photon blockade. By tuning the system towards or away from an EP, one can control quantum correlations, implying the potential use of their system for frequency tunable single‐photon generation and an antibunching‐to‐bunching light switch. The work sheds new light on EP‐engineered purely quantum effects, providing unique opportunities for making and utilizing various single‐photon quantum EP devices.

Single-photon blockade in quasichiral atom–photon interaction: simultaneous high purity and high efficiency

“…Furthermore, the maximum chirality always achieves at φ = π/2 and φ = 3π/2 and is irrespective to the coupling strengths. Similar asymmetrical or even chiral coupling have been reported in other quantum systems, such as two circularly polarized QEs above the metal surface [27,28], the clockwise (CW) and counterclockwise (CCW) modes in a nonlinear whispering-gallery-mode (WGM) resonator [29], and the microwave circuit mediated magnon-photon coupling [30].…”

Harnessing Anti‐Parity‐Time Phase Transition in Coupled Topological Photonic Valley Waveguides

“…Since the exceptional point of our system manifests zero group velocity (as shown in Figure 3c), which could decelerate the light and enhance the light-matter interactions, [55,56] our work provides easily-implementable platforms to study the quantumexceptional-point resulted in intriguing phenomena. [57,58] Our platform could further interface with crystalline symmetries, [59] synthetic dimensions, [35,60] gain/dissipative media, [33][34][35]61] nonlinearity, [35,55,56] or quantum effects [62] and give rise to more intriguing non-Hermitian topological phenomena, nonlinear optics, or topological quantum optics. These findings may also be extended to other wave systems, such as acoustic or mechanical systems.…”

Hybrid photon-phonon blockade

“…A number of generalizations of the standard single-PB were proposed, which include: (i) two-and multi-photon versions of PB, as first predicted in [24,25] and demonstrated experimentally in [10,26]; (ii) unconventional PB as predicted in [27] and experimentally demonstrated in [11,12]; (iii) Conventional and unconventional nonreciprocal PB effects as predicted in [28,29] and (at least partially) confirmed experimentally in [30]; (iv) statedependent PB [31], (v) exceptional PB [32], (vi) dispersive PB [7], and (vii) linear quantum scissors based on conditional measurements for: single-PB [33][34][35], which was experimentally demonstrated in [36], as well as two-PB [37], and multi-PB [38,39] using multiport Mach-Zehnder interferometers [40]. This probabilistic approach to PB enables also quantum teleportation and more selective optical-state truncations, e.g, hole burning in the Hilbert space [41].…”