Dimensions, nodes and phases in quantum numbers

任意相位CZ门及跨空间分离超导节点间的远程读取

Arbitrary-phase CZ gate and remote readout across spatially separated superconducting nodes

本研究在跨空间分离的超导节点间实现了任意相位CZ门，通过双向光子传输协议调谐条件相位，并实现了无需远程节点主动参与的远程单发读取，为分布式量子计算提供了基础操作。

Phase space patterns of quantum transport on ordered and disordered networks

In this paper, we consider the quantum-mechanical phase space patterns on ordered and disordered networks. For ordered networks in which each node is connected to its 2m nearest neighbors (m on either side), the phase space quasi-probability of Wigner function shows various patterns. In the long time limit, on even-numbered networks, we find an asymmetric quasi-probability between the node and its opposite node. This asymmetry depends on the network parameters and specific phase space positions. For disordered networks in which each edge is rewired with probability p>0, the phase space display…

Broadcast Classical-Quantum Capacity Region of Two-Phase Bidirectional Relaying Channel

We study a three-node quantum network which enables bidirectional communication between two nodes with a half-duplex relay node. A decode-and-forward protocol is used to perform the communication in two phases. In the first phase, the messages of two nodes are transmitted to the relay node. In the second phase, the relay node broadcasts a re-encoded composition to the two nodes. We determine the capacity region of the broadcast phase.

Greenberger-Horne-Zeilinger test for multi-dimension and arbitrary time nodes entangled histories

Based on the framework of consistent history theory, the quantum entangled history was proposed in 2015 and experimentally verified through temporal Greenberger-Horne-Zeilinger (GHZ) test with $3$ time nodes in 2016. In this paper, we extend the temporal GHZ test to arbitrary time nodes and even system dimensions. Then, we define a witness to distinguish between the quantum entangled histories and the classical histories. The minimums of the witness for the classical histories are calculated for arbitrary number of time nodes and the system dimensions $2$ and $\infty$. It is found that the min…

Hidden Single-Qubit Topological Phase Transition without Gap Closing in Anisotropic Light-Matter Interactions

Conventionally the occurrence of topological phase transitions (TPTs) requires gap closing, whereas there are also unconventional cases without need of gap closing. Although traditionally TPTs lie in many-body systems in condensed matter, both cases of TPTs may find analogs in few-body systems. Indeed, the ground-state node number provides a topological classification for single-qubit systems. While the no-node theorem of spinless systems is shown to also restrict the fundamental quantum Rabi model in light-matter interactions, it is demonstrated that the limitation of the no-node theorem can …

Quantum computations on the ensemble of two-node cluster states, obtained by sub-Poissonian lasers

In this study, we demonstrate the possibility of the implementation of universal Gaussian computation on a two-node cluster state ensemble. We consider the phase-locked sub-Poissonian lasers, which radiate the bright light with squeezed quadrature, as the resource to generate these states.