In this article, we consider a spin-spin interaction network governed by $XX + YY$ Hamiltonian. The vertices and edges of the network represent the spin objects and their interactions, respectively. We take a privilege to switch on or off any interaction, that assists us to perform multiple perfect state transfers in a graph simultaneously. We also build up a salable network allowing quantum communication between two arbitrary vertices. Later we utilize the combinatorial characteristics of hypercube graphs to propose a static routing schema to communicate simultaneously between a set of senders and a set of receivers in a planar network. Our construction is new and significantly powerful. We elaborate multiple examples of planar graphs supporting quantum routing where classical routing is not possible.
Quantum switching networks for perfect qubit routing
我们发展了Christandl et al. [M. Christandl，N.达塔，T。C. Dorlas，A. Ekert，A. Kay和A. J. Landahl，Phys.Rev.A71，032312（2005）]，以示出d-超立方体同质网络如何可以通过附加链路来修饰，以在独立于所选择的路由并且令人惊讶地独立于网络的大小的持续时间内在任何给定的输入和输出节点之间完美地路由量子信息。
We exhibit a strong connection between the matchgate formalism introduced by Valiant and the ZW-calculus of Coecke and Kissinger. This connection provides a natural compositional framework for matchgate theory as well as a direct combinatorial interpretation of the diagrams of ZW-calculus through the perfect matchings of their underlying graphs. We identify a precise fragment of ZW-calculus, the planar W-calculus, that we prove to be complete and universal for matchgates, that are linear maps satisfying the matchgate identities. Computing scalars of the planar W-calculus corresponds to countin…
We propose a hypercube switching architecture for the perfect state transfer (PST) where we prove that it is always possible to find an induced hypercube in any given hypercube of any dimension such that PST can be performed between any two given vertices of the original hypercube. We then generalise this switching scheme over arbitrary number of qubits where also this routing feature of PST between any two vertices is possible. It is shown that this is optimal and scalable architecture for quantum computing with the feature of routing. This allows for a scalable and growing network of qubits.…
The transfer of data is a fundamental task in information systems. Microprocessors contain dedicated data buses that transmit bits across different locations and implement sophisticated routing protocols. Transferring quantum information with high fidelity is a challenging task, due to the intrinsic fragility of quantum states. We report on the implementation of the perfect state transfer protocol applied to a photonic qubit entangled with another qubit at a different location. On a single device we perform three routing procedures on entangled states with an average fidelity of 97.1%. Our pro…
Quantum Technology Lab, Dipartimento di Fisica Aldo Pontremoli , Università di Milano（米兰大学阿尔多·蓬特罗莫利物理系量子技术实验室）；Dipartimento di Scienze Fisiche, Informatiche e Matematiche, Università di Modena e Reggio Emilia（摩德纳和雷焦艾米利亚大学物理、信息和数学科学系）；Centro S3, CNR-Istituto di Nanoscienze（CNR纳米科学研究所S3中心）；INFN, Sezione di Milano（意大利国家核物理研究所米兰分部）
We study the quantum interference between different weak signals in a three-port optomechanical system, which is achieved by coupling three cavity modes to the same mechanical mode. If one cavity serves as a control port and is perturbed continually by a control signal, nonreciprocal quantum interference can be observed when another signal is injected upon different target ports. In particular, we exhibit frequency-independent perfect blockade induced by the completely destructive interference over the full frequency domain. Moreover, coherent photon routing can be realized by perturbing all p…
High-dimensional quantum systems can offer extended possibilities and multiple advantages while developing advanced quantum technologies. In this paper, we propose a class of quantum-walk architecture networks that admit the efficient routing of high-dimensional quantum states. Perfect state transfer of an arbitrary unknown qudit state can be achieved between two arbitrary nodes via a one-dimensional lackadaisical discrete-time quantum walk. In addition, this method can be generalized to the high-dimensional lattices, where it allows distillable entanglement to be shared between arbitrary inpu…
Bounded-depth spacetime lattice surgery for resource-efficient fault-tolerant quantum computation
Graduate School of Information Science and Technology, The University of Tokyo（东京大学大学院信息理工学系研究科）；Center for Quantum Computing, RIKEN（理化学研究所量子计算中心）；Faculty of Information Science and Electrical Engineering, Kyushu University（九州大学情报理工学府）；International Center for Elementary Particle Physics, The University of Tokyo（东京大学国际基本粒子物理中心）
In an effort to overcome the limitations of random spin-glass benchmarks for quantum annealers, focus has shifted to carefully-crafted gadget-based problems whose logical structure has typically a planar topology. Recent experiments on these gadget problems using a commercially-available quantum annealer have demonstrated an impressive performance over a selection of commonly-used classical optimization heuristics. Here we show that efficient classical optimization techniques, such as minimum-weight perfect matching, can solve these gadget problems exactly and in polynomial time. We present ap…
