Universal photonic three-qubit quantum gates with two degrees of freedom assisted by charged quantum dots inside single-sided optical microcavities

Abstract

Although universal quantum computation can be realized with two-qubit controlled-not (CNOT) gates and single-qubit rotations, it would be convenient to have resource-efficient and robust multiqubit quantum gates in practical quantum information processing. Here we present two new schemes to determinately implement three-qubit Toffoli gate and Fredkin gate on photon systems with two degrees of freedom (DOFs), assisted by charged quantum dots (QDs) inside single-sided optical microcavities. In contrast to the traditional Toffoli and Fredkin gates operating in photonic one DOF, the gates presented here with two DOFs can reduce the photon numbers required to implement the gate operations. Compared with the ones synthesized by CNOT and single-qubit gates, the present gates can reduce the complexity in experiment. Our schemes exploit the robust giant circular birefringence induced by a singleelectron spin in a QD-cavity system, which do not require photon indistinguishability or photon interference as demanded by other schemes using linear optics. Moreover, additional ancillary photons are not required in the schemes. We discuss the feasibility of our schemes, concluding that they can be realized with current or near-future technologies.

Hyperparallel transistor, router and dynamic random access memory with unity fidelities

“…From Eqs. ( 25)- (31), one can see that Fig. 4 accomplished a hyper-router acting on the polarization and spatial DOFs.…”

“…Quantum teleportation with multiple DOFs [4], complete hyperentangled-Bell-(Greenberger-Horne-Zeilinger-) state analysis [17][18][19], hyperparallel quantum repeater [20], hyperentanglement concentration [21][22][23][24][25][26], and hyperentanglement purification [27,28] have been proposed for high-capacity long distance quantum communication. Hyperparallel quantum computing also attracted much attention and made a series of outstanding achievements as its promising merits, especially in the field of hyper-parallel universal quantum gates [29][30][31].…”

Complete Hyperentangled Bell States Analysis For Polarization‐Spatial‐Time‐Bin Degrees of Freedom with Unity Fidelity

“…Such two schemes were further improved to the error-detected ones by Wang et al, [57] Zheng et al, [58] and Cao et al [59] QDs, named as artificial atom, have been recognized as the promising candidates for QIP. [63][64][65][66][67][68][69][70][71][72][73][74][75][76][77][78] Nowadays, schemes for implementing quantum gates have been proposed in hybrid photon-QD systems, [63][64][65] solid-QD systems, [66,67] and flying photon systems, [68,69] respectively. Quantum entanglements between a QD spin and a single photon [70] and between two distance QD hole spins [71] have been experimentally demonstrated.…”

Complete hyperentangled Bell states analysis for polarization-spatial-time-bin degrees of freedom with unity fidelity

“…Such two schemes were further improved to the error-detected ones by Wang et al, [57] Zheng et al, [58] and Cao et al [59] QDs, named as artificial atom, have been recognized as the promising candidates for QIP. [63][64][65][66][67][68][69][70][71][72][73][74][75][76][77][78] Nowadays, schemes for implementing quantum gates have been proposed in hybrid photon-QD systems, [63][64][65] solid-QD systems, [66,67] and flying photon systems, [68,69] respectively. Quantum entanglements between a QD spin and a single photon [70] and between two distance QD hole spins [71] have been experimentally demonstrated.…”