Deterministic CNOT gate and entanglement swapping for photonic qubits using a quantum-dot spin in a double-sided optical microcavity

Abstract

We propose a deterministic and scalable scheme to construct a two-qubit controlled-NOT (CNOT) gate and realize entanglement swapping between photonic qubits using a quantum-dot (QD) spin in a double-sided optical microcavity. The scheme is based on spin selective photon reflection from the cavity and can be achieved in a nondestructive and heralded way. We assess the feasibility of the scheme and show that the scheme can work in both the weak coupling and the strong coupling regimes. The scheme opens promising perspectives for long-distance photonic quantum communication and distributed quantum information processing.

Efficient spin Bell states and Greenberger–Horne–Zeilinger states analysis in the quantum dot–microcavity coupled system

“…The extent of variables in the Figs. 4, 5, 6, and Tables 3, 4, 5, and 6 are commonly adopted in numerous pervious schemes [58,89,90] with weak-coupling QDs and microcavities systems. We can see from the tables and figures that the fidelities and the successful probabilities will increase when g/κ increases and κ s /κ decreases.…”

Can a universal quantum cloner be used to design an experimentally feasible near-deterministic CNOT gate?

“…The two photons come successively to interact with the optical micro-cavity. For the coupled cavity, when considering equal the frequencies of the input photon, cavity mode and the spin-dependent optical transition, the reflection and transmission coefficients of the double sided optical micro-cavity system used in the CNOT design, are denoted r (ω) and t (ω), respectively, and are given by: 20,22,33…”

“…In this case, t (ω) in the coupled cavity and r 0 (ω) in the uncoupled cavity will introduce bit-flip errors. Relevant energy levels and optical selection rules for exciton X − inside the single charged GaAs/ InAs QD, have been well detailed in, 19,20 and the dynamics of the interaction of the QD spin in a double sided optical micro-cavity, for r 0 = |r 0 (ω)|, t 0 = |t 0 (ω)|, r 1 = |r (ω)| and t 1 = |t (ω)|, are given as follows:…”

“…This is because of physical constraints that make them less effective in serial or parallel combinations. For the special CNOT model of Wang et al , 20 we presented comments on the parametric values taken for the simulation and showed that the proposed CNOT gate is valid only in the strong coupling regime. 23 In this paper, we refer to this same CNOT and show that it provides a fidelity of only 47% in a realistic implementation (while it is 93.7% in the theoretical case), then we propose an optimized design based on a quantum cloner.…”

Scheme for generating the singlet state of three atoms trapped in distant cavities coupled by optical fibers

“…Entangled states have many promising practical applications in different areas such as quantum computing [1][2][3][4][5], quantum teleportation [6][7][8], quantum cryptography [9,10], quantum dense coding [11], precision measurements [12] and quantum information processing [13,14]. Over the past few years, a large number of schemes have been proposed to generate entangled states in various physical systems, including cavity quantum electrodynamics (QED) [15][16][17][18][19], trapped ions [20,21], semiconductor quantum dots [22], linear optics [23][24][25], and so on.…”