Strong Photon Blockade Mediated by Optical Stark Shift in a Single-Atom–Cavity System

Abstract

We propose a theoretical scheme to achieve strong photon blockade via a single atom in cavity. By utilizing optical Stark shift, the dressed-state splitting between higher and lower branches is enhanced, which results in significant increasing for lower (higher) branch and decreasing for higher (lower) branch at the negative (positive) Stark shift, and dominates the time-evolution of photon number oscillations as well. Furthermore, the two-photon excitation is suppressed via quantum interference under optimal phase and Rabi frequency of an external microwave field. It is shown that the interplay between the quantum interference and the enhanced vacuum-Rabi splitting gives rise to a strong photon blockade for realizing high-quality single photon source beyond strong atomcavity coupling regime. In particular, by tuning the optical Stark shift, the second-order correlation function for our scheme has three orders of magnitude smaller than Jaynes-Cummings model and correspondingly there appears a large cavity photon number as well. Our proposal may implicate exciting opportunities for potential applications on quantum network and quantum information processing.

Tunable Photon blockade with single atom in a cavity under electromagnetically induced transparency

“…1(c) and 1(d) show the dressed-state splitting 1, as a function of Stark shift 0 for weak (Ω/ = 0.01) and strong (Ω/ = 2.1) control fields by fixing / = 4, respectively, where = ±1, 0 represents the upper, lower, and middle helicity branches, respectively. An asymmetry structure of the dressed-state splitting between the red and blue light-cavity detuning is observed, where the result is analogous to our recent study on the Stark shift mediated Jaynes-Cummings model [37]. Moreover, the 0 -dependent lower branch splitting 1,− is significantly enhanced with the increasing negative | 0 |, while gradually saturated to a constant for positive 0 , vice verse for the case of the higher branch splitting 1,+ .…”

“…( 4) as well. In contrast to the spin-1/2 model [37], the (2) (0) does not exhibit a significant reduction with the enhanced PB, even for a large | 0 |. It is understood that the quantum interference mechanism for realizing strong PB is absent in our cavity-EIT model at the vacuum-Rabi splitting (Δ = 1,± ), which reveals that the Stark shift enhanced energy-spectrum anharmonicity is not sufficient to guarantee the strong PB.…”

“…As a result, the photon quantum statistics for PB should satisfy both the subPoissonian statistics with (2) (0) < 1 and photon antibunching with (2) (0) < (2) ( ), simultaneously. Without loss of generality, the strong PB is defined as (2) (0) < 0.01, where photon antibunching is confirmed by using the quantum regression theorem [37].…”

“…Meanwhile, our scheme has the following advantages in contrast to the Stark shift mediated Jaynes-Cummings model [37]. (i) Our scheme does not require the quantum interference conditions, which rely on the precise control of the phase and the coupling strength of an external microwave field simultaneously.…”

“…In particular, unconventional PB has been experimentally demonstrated in single quantum dot-cavity system and two coupled superconducting resonators [35,36] by utilizing the constructive quan-tum interference to suppress the two-photon excitation. However, our recent work shows that the quantum interference mechanism for generating strong PB [ (2) (0) ∼ 0] is still a challenge for the weak atom-cavity coupling regime [37], which indicates that sufficient energy-spectrum anharmonicity is necessary for most of the systems. In general, multiphoton excitation plays an important role in the system with weak energy-spectrum anharmonicity, although the twophoton excitation could be completely suppressed by quantum interference for unconventional PB.…”