International Journal of Quantum Information

In this paper, we propose how to achieve nonreciprocal unconventional photon blockade (NUPB) in a spinning system consisting of two single-mode cavities with ${\chi }^{(2)}$ nonlinearity through the Fizeau drag when the two cavities are driven simultaneously. Under the weak driving condition, we discuss the physical origins of nonreciprocal unconventional photon blockade, which originates from the destructive interference between different paths from the ground state to the two-photon state by driving the device from the left side. While the quantum interference paths are broken when the device is driven from the right side, resulting in photon bunching. The optimal condition for the nonreciprocal unconventional photon blockade is analytically derived. We also calculate the analytical expression of the delayed-time second-order correction function and compare it with the numerical simulation. Finally, we show that nonreciprocal unconventional photon blockade never occurs with a single driving since two closed quantum pathways cannot be formed.

In quantum mechanics, quantum discord is a valuable quantum resource. As a generalization of the initial quantum discord, the multipartite quantum discord (MQD) exhibits excellent properties in the complete monogamy relation. In this paper, the dynamics of MQD are investigated for the Greenberger–Horne–Zeilinger (GHZ) state in Markovian environments. More specifically, it indicates that MQD of the GHZ state drops significantly over time in the depolarizing noise channel. Interestingly, quantum decoherence has no influence on MQD of the GHZ state in the Pauli channel ${\sigma }_z$. Subsequently, the analytical formulas of MQD are derived with six parameters in the Pauli channels ${\sigma }_x$ and ${\sigma }_y$, respectively. This is conducive to more efficient use of the GHZ state for various quantum tasks.

Quantum maximum-distance-separable (MDS) codes play an important role in the quantum codes. The previous quantum MDS codes had been constructed according to $q$ is odd or even. However, such classification omits to consider some special categories of quantum MDS codes. Because of this, we will discuss the other classifications of $q$. In this paper, we construct some new $q$-ary quantum MDS codes from generalized Reed–Solomon codes by using Hermitian construction, and prove that these quantum MDS codes have minimum distance greater than $\frac{q}{2}$, where $q\equiv -1(mod3)$.

This paper proposes an Efficient Framework for Quantum Video (EFQV) in quantum computer. EFQV adds time index information into different frames on BRQI (a Quantum Image Representation based on Bitplanes, BRQI) images, and each bitplanes quantum image adds a time index. Complement of Colors (COC) operator, Reverse of Bitplanes (ROB) operator, and Shift of Frames (SOF) operator are designed for EFQV and its operators are tested on the IBM quantum computation framework qiskit. Experimental results show the effectiveness of EFQV and its operations on quantum computing environment. Compared with other frameworks, EFQV has advantages in time complexity and quantum cost.

We have established a novel method to detect non-Markovian indivisible quantum channels using structural physical approximation. We have shown that this method can be used to detect eternal non-Markovian operations. We have further established that harnessing eternal non-Markovianity, we can device a protocol to detect quantum entanglement.