A scheme for a conditional quantum phase gate using a bimodal cavity and a ladder-type three-level atom

Abstract

A scheme is proposed to implement a two-qubit conditional quantum phase gate for the intracavity field using a single ladder-type three-level atom driven by two modes in a high-Q cavity. The quantum information is encoded on the Fock states of a bimodal cavity. The averaged fidelity of the gate can be expected to reach 99:86%.

A Simple Scheme for Realizing a Multiqubit Controlled-Phase Gate Through a Resonant Interaction of Three-Level Atoms with a Single-Mode Cavity

“…Very recently, three important proposals about quantum phase gate of photonic qubits using a single three-level atom with Ξ-type, [15] V -type, [16] or Λ-type configuration [17] have been reported, among which zeroand one-photon Fock states of two intracavity modes are encoded as logic zero and one qubits. In particular, Dong [18] et al put forward an efficient scheme for realizing a two-qubit phase gate of photonic qubits through the dispersive interaction between a Λ-type atom and two polarized quantized cavity modes in 2009.…”

“…In addition, in Refs. [15][16][17][18] all the logical states are encoded into the two cavity-fields, which are difficult to extend their schemes to achieve the N -qubit phase gate, the proposal in this paper can be applied to realize an Nqubit phase gate in the N − 1 atoms case. The present method has the following advantages: (i) During the operation, two stable ground states of atom are encoded as qubits, which have the energy lower than the other atomic states and can be relatively stable in experiment.…”