Photon Routing in Cavity QED: Beyond the Fundamental Limit of Photon Blockade

TL;DR

This paper investigates the fundamental limits of photon blockade in cavity QED, revealing inherent constraints due to quantum uncertainty and proposing a three-level atom system to achieve ideal photon routing.

Contribution

It uncovers the fundamental quantum limits of photon blockade in cavity QED and introduces a three-level atom scheme to surpass these limits for perfect photon routing.

Findings

Time-energy uncertainty limits photon blockade efficiency.

Strong coupling and bad cavity regimes exhibit similar blockade behavior.

Three-level atom system enables perfect photon routing.

Abstract

The most simple and seemingly straightforward application of the photon blockade effect, in which the transport of one photon prevents the transport of others, would be to separate two incoming indistinguishable photons to different output ports. We show that time-energy uncertainty relations inherently prevent this ideal situation when the blockade is implemented by a two-level system. The fundamental nature of this limit is revealed in the fact that photon blockade in the strong coupling regime of cavity QED, resulting from the nonlinearity of the Jaynes-Cummings energy level structure, exhibits efficiency and temporal behavior identical to those of photon blockade in the bad cavity regime, where the underlying nonlinearity is that of the atom itself. We demonstrate that this limit can be exceeded, yet not avoided, by exploiting time-energy entanglement between the incident photons. Finally, we show how this limit can be circumvented completely by using a three-level atom coupled to a single-sided cavity, enabling an ideal and robust photon routing mechanism.