Photonic ququart logic assisted by the cavity-QED system.
Universal quantum logic gates are important elements for a quantum computer. In contrast to previous constructions of qubit systems, we investigate the possibility of ququart systems (four-dimensional states) dependent on two DOFs of photon systems. We propose some useful one-parameter four-dimensional quantum transformations for the construction of universal ququart logic gates. The interface between the spin of a photon and an electron spin confined in a quantum dot embedded in a microcavity is applied to build universal ququart logic gates on the photon system with two freedoms. Our elementary controlled-ququart gates cost no more than 8 CNOT gates in a qubit system, which is far less than the 104 CNOT gates required for a general four-qubit logic gate. The ququart logic is also used to generate useful hyperentanglements and hyperentanglement-assisted quantum error-correcting code, which may be available in modern physical technology.
Information Security and National Computing Grid Laboratory, Southwest Jiaotong University, Chengdu 610031, China.
Ming-Xing
MX
Luo
School of Computer Science, Sichuan University of Science &Engineering, Zigong 64300, China.
Yun
Y
Deng
Information Security and National Computing Grid Laboratory, Southwest Jiaotong University, Chengdu 610031, China.
Hui-Ran
HR
Li
School of Mathematics and Statistics, Henan University, Kaifeng 475004, China.
Song-Ya
SY
Ma