Multiple multicontrol unitary operations: Implementation and applications

Lin, Qing

doi:10.1007/s11433-017-9140-8

Cited by 3 publications

(4 citation statements)

References 118 publications

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“…In Table , we compare the physical resources and the optical elements needed in three schemes with the present one. Based on the spatial and polarization degrees of freedom, the number of spatial paths of the target photon is 2 n in the former three schemes, while it is 2 in the present scheme with the help of the temporal degree of freedom.…”

Section: Discussion and Summarymentioning

confidence: 99%

“…That is,

2^{n} - 1

2^{n} - 1

and 2 n are necessary for control‐path process, merging process, and coherent state interference process in the schemes of refs. [] and [], while

2^{n} - 1

and

n \cdot 2^{n - 1}

are needed for control‐path process and output process in the scheme of ref. [].…”

Section: Discussion and Summarymentioning

confidence: 99%

“…For refs. [] and [], the coherent state can be repeatedly employed, which can reduce the employment of coherent states largely. However, one BS and one BS process for coherent state interference process needs to be introduced in order to save one coherent state.…”

Section: Discussion and Summarymentioning

confidence: 99%

“…Besides two‐photon quantum gates, some three‐photon quantum gates are also the reversible and universal logic gates for quantum computation, such as a Fredkin gate and a Toffoli gate . Assisted by strong and weak cross‐Kerr nonlinearities, the Fredkin gate and the Toffoli gate with high success probability can be constructed, where the spatial degree of freedom is applied to assist their construction. Relying on the assistance of the spatial degree of freedom, multiphoton polarization controlled logic gates attract much attention …”

Section: Introductionmentioning

confidence: 99%

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Construction of a Polarization Multiphoton Controlled One‐Photon Unitary Gate Assisted by the Spatial and Temporal Degrees of Freedom

et al. 2019

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In order to fulfill quantum information processing tasks such as quantum computation and scalable quantum networks, quantum logic gates are indispensable parts. A multiqubit logic gate can efficiently reduce the cost of physical resources and complicated operations that are necessary in the combination of fewer-qubit (e.g., two-qubit) logic gates to fulfill the same tasks. However, the construction of multiphoton quantum logic gates is a large challenge. Assisted by spatial and temporal degrees of freedom, a polarization multiphoton controlled one-photon unitary gate is proposed, which can be realized with three processes including the control-path process based on weak cross-Kerr nonlinearities, the unitary transformation process, and the output process. In the control-path process, the control-path modules are applied, where the entanglement between polarization, spatial and temporal degrees of freedom is generated by beam splitters, time delayers, and nonlinear interaction in cross-Kerr media. The scheme presented here, assisted by spatial and temporal degrees of freedom reduces the experimental complexity of the schemes assisted by only spatial degree of freedom. Moreover, it will also be a useful reference in optimally constructing multiqubit quantum logic gates with other multiple degrees of freedom in many physical systems.variety of physical systems in the theoretical aspect [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] and experimental aspect. [21][22][23][24][25][26] Photons are the promising carriers of quantum information due to their advantages, fast propagation, low decoherence, ease to manipulate, etc. [27] However, owing to weak photon-photon interaction, quantum logic gates at the single-photon level had made slow progress. [22] The linear optics standard model proposed by Knill et al. [28] had changed this unclear situation, while its upper limitation of success probability is less than unity. [29] Furthermore, by using nonlinear optical interaction such as cross-Kerr interaction, the threshold on the success probability imposed by the linear optics standard model could be broken through. [30] Due to tiny strength of nonlinear interaction, the direct applications of cross-Kerr nonlinearities have not been easily realized. To achieve feasibility of deterministic quantum logic gates, weak cross-Kerr nonlinearities were applied first in the two-photon controllednot gate using an auxiliary photon, [31] which approaches the success probability nearly close to unity. After that, many construction schemes of twophoton logic gates based on weak cross-Kerr nonlinearities were proposed, for instance, the controlled-not gate with half unity success probability without an auxiliary photon, [32] the controllednot gate, [33] and the controlled-phase gate [34] with nearly unity success probability without the auxiliary photon, quantum logic gates [35] composed by control-path gate and merging gate. On the other hand, weak cross-Kerr nonlinearities were also used in the Bell states analys...

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Section: Discussion and Summarymentioning

confidence: 99%

“…That is,