A scheme for direct implementation of a two-target qubit controlled phase gate with quantum dots in coupled photonic crystal cavities without using classical laser pulses

Abstract

We propose a scheme to implement a three-qubit controlled phase gate with one control qubit and two target qubits using quantum dots (QDs) in two coupled photonic crystal (PC) cavities A and B. In the scheme, three QDs are embedded in two coupled photonic crystal cavities and the transitions between the levels are only coupled to the cavity modes without being driven by the classical laser fields. We investigate the dynamics of the system consisting of resonant and off-resonant couplings between the cavity modes and QDs and solve the time-dependent Schrödinger equation analytically. The results show that a three-qubit controlled phase gate can be directly implemented using one operational step, by exchanging a single photon between the PC cavities A and B. This scheme greatly simplifies the gate operation in experiments.