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Faithfully transferring the quantum state is essential for quantum information processing. Here we demonstrate a fast (in 84 ns) and high-fidelity (99.2%) transfer of arbitrary quantum states in a chain of four superconducting qubits with…

Quantum Physics · Physics 2018-11-09 X. Li , Y. Ma , J. Han , Tao Chen , Y. Xu , W. Cai , H. Wang , Y. P. Song , Zheng-Yuan Xue , Zhang-qi Yin , Luyan Sun

We introduce and study peak state transfer, a notion of high state transfer in qubit networks modeled by continuous-time quantum walks. Unlike perfect or pretty good state transfer, peak state transfer does not require fidelity arbitrarily…

Quantum Physics · Physics 2025-10-02 Gabriel Coutinho , Krystal Guo , Vincent Schmeits

A discrete-time quantum walk is the quantum analogue of a Markov chain on a graph. Zhan [J. Algebraic Combin. 53(4):1187-1213, 2020] proposes a model of discrete-time quantum walk whose transition matrix is given by two reflections, using…

Combinatorics · Mathematics 2022-11-24 Krystal Guo , Vincent Schmeits

The XX model with uniform couplings represents the most natural choice for quantum state transfer through spin chains. Given that it has long been established that single-qubit states cannot be transferred with perfect fidelity in this…

Quantum Physics · Physics 2014-12-04 Rúben Sousa , Yasser Omar

We study quantum state transfer through a qubit network modeled by spins with XY interaction, when relying on a single excitation. We show that it is possible to achieve perfect transfer by shifting (adding) energy to specific vertices.…

Quantum Physics · Physics 2010-01-20 Andrea Casaccino , Seth Lloyd , Stefano Mancini , Simone Severini

We study the existence of quantum state transfer on non-integral circulant graphs. We find that continuous time quantum walks on quantum networks based on certain circulant graphs with $2^k$ $\left(k\in\mathbb{Z}\right)$ vertices exhibit…

Combinatorics · Mathematics 2019-01-09 Hiranmoy Pal

Quantum walks are a well-established model for the study of coherent transport phenomena and provide a universal platform in quantum information theory. Dynamically influencing the walker's evolution gives a high degree of flexibility for…

We present a method that implement directional, perfect state transfers within a branched spin network by exploiting quantum interferences in the time-domain. That provides a tool to isolate subsystems from a large and complex one.…

We study the routing of quantum information in parallel on multi-dimensional networks of tunable qubits and oscillators. These theoretical models are inspired by recent experiments in superconducting circuits using Josephson junctions and…

Quantum Physics · Physics 2015-05-19 Christopher Chudzicki , Frederick W. Strauch

The goal in quantum state transfer is to avoid the need to physically transport carriers of quantum information. This is achieved by using a suitably engineered Hamiltonian that induces the transfer of the state of one subsystem to another.…

The issue of quantum states' transfer -- in particular, for so-called Perfect State Transfer (PST) -- in the networks represented by the spin chains seems to be one of the major concerns in quantum computing. Especially, in the context of…

Quantum Physics · Physics 2013-02-05 Marek Sawerwain , Joanna Wiśniewska

In this paper, we analyze state transfer in quantum walks by using combinatorial methods. We generalize perfect state transfer in two-reflection discrete-time quantum walks to a notion that we call 'peak state transfer'; we define peak…

Combinatorics · Mathematics 2025-01-14 Krystal Guo , Vincent Schmeits

We present a communication protocol for chains of permanently coupled qubits which achieves perfect quantum state transfer and which is efficient with respect to the number chains employed in the scheme. The system consists of $M$ uncoupled…

Quantum Physics · Physics 2009-11-10 Daniel Burgarth , Vittorio Giovannetti , Sougato Bose

We show how two many-body, generally mixed, quantum states can be swapped via collective, all-to-all interactions. Specifically, we present an experimentally relevant implementation for quantum dots that enables coherent exchange of quantum…

Quantum Physics · Physics 2025-08-19 Matthew Wampler , Nigel R. Cooper

In a continuous-time quantum walk on a network of qubits, pretty good state transfer is the phenomenon of state transfer between two vertices with fidelity arbitrarily close to 1. We construct families of graphs to demonstrate that there is…

Combinatorics · Mathematics 2023-05-24 Ada Chan , Peter Sin

Effective state transfer is one of the most important problems in quantum information processing. Typically, a quantum information device is composed of many subsystems with multi-input ports. In this paper, we develop a general theory…

Quantum Physics · Physics 2016-08-23 Naoki Yamamoto , Hendra I. Nurdin , Matthew R. James

We investigate quantum state transfer on a class of bipartite graphs, namely the butterfly graphs, within the framework of discrete-time quantum walks. These graphs facilitate the construction of scalable quantum networks that enable…

Quantum Physics · Physics 2026-04-14 Monika Rani , Subhashish Banerjee , Nikhil Swami , Supriyo Dutta

Efficient quantum-state transfer is achieved in a uniformly coupled spin-1/2 chain, with open boundaries, by application of local magnetic fields on the second and last-but-one spins, respectively. These effective \textit{barriers} induce…

Quantum Physics · Physics 2015-06-12 S. Lorenzo , T. J. G. Apollaro , A. Sindona , F. Plastina

Superconducting quantum circuits, fabricated with multiple layers, are proposed to implement perfect quantum state transfer between nodes of a hypercube network. For tunable devices such as the phase qubit, each node can transmit quantum…

Quantum Physics · Physics 2009-11-13 Frederick W. Strauch , Carl J. Williams

We experimentally demonstrate the transfer of an unknown single-qubit state from Alice to Bob via a two-step discrete-time quantum random walk on a cycle with four vertices on a four-qubit nuclear magnetic resonance quantum processor. The…

Quantum Physics · Physics 2024-11-05 Gayatri Singh , Kavita Dorai , Arvind