Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:quant-ph/0407058 · Physical Review A

Quantum-state transfer in imperfect artificial spin networks

Mauro Paternostro, G. Massimo Palma, M. S. Kim, G. Falci

Published Apr 5, 2005• 65 citations
arXivHTMLPDF

Abstract

High-fidelity quantum computation and quantum state transfer are possible in short spin chains. We exploit a system based on a dispersive qubit-boson interaction to mimic XY coupling. In this model, the usually assumed nearest-neighbor coupling is no longer valid: all the qubits are mutually coupled. We analyze the performances of our model for quantum state transfer showing how preengineered coupling rates allow for nearly optimal state transfer. We address a setup of superconducting qubits coupled to a microstrip cavity in which our analysis may be applied.

DOI
10.1103/physreva.71.042311

Related papers

Perfect Quantum State Transfer in a Superconducting Qubit Chain with Parametrically Tunable Couplings

Xuegang Li, Y. Ma, J. Han +8 more

Quantum information processing requires faithful on-chip transfer of quantum states, but the couplings in solid-state systems are usually preset and not tunable, and thus in general cannot meet the special configurations needed for perfect quantum state transfer. The authors demonstrate such a perfect transfer in a chain of four superconducting qubits with nearest-neighbor coupling through $i\phantom{\rule{0}{0ex}}n$ $s\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}u$ parametric modulation, in a single step, with high fidelity (99.2%) in a short time (84 ns), thus overcoming the fixed-coupling problem. Their scheme for flexible tunability of multiqubit coupling can be easily extended to larger systems.

arXiv:1806.03886•Physical Review Applied•Nov 5, 2018•173 citations

Exploiting boundary states of imperfect spin chains for high-fidelity state transfer

M. Bruderer, Kurt Franke, S. Ragg +2 more

We study transfer of a quantum state through $XX$ spin chains with static imperfections. We combine the two standard approaches for state transfer based on (i) modulated couplings between neighboring spins throughout the spin chain and (ii) weak coupling of the outermost spins to an unmodulated spin chain. The combined approach allows us to design spin chains with modulated couplings and localized boundary states, permitting high-fidelity state transfer in the presence of random static imperfections of the couplings. The modulated couplings are explicitly obtained from an exact algorithm using the close relation between tridiagonal matrices and orthogonal polynomials [Linear Algebr. Appl. 21, 245 (1978)]. The implemented algorithm and a graphical user interface for constructing spin chains with boundary states (spinGUIn) are provided as Supplemental Material.

arXiv:1112.4503•Physical Review A•Feb 9, 2012•41 citations

Quantum communication in spin systems with long-range interactions

M. Avellino, Andrew J. Fisher, Sougato Bose

We calculate the fidelity of transmission of a single qubit between distant sites on semi-infinite and finite chains of spins coupled via the magnetic dipole interaction. We show that such systems often perform better than their Heisenberg nearest-neighbor coupled counterparts, and that fidelities closely approaching unity can be attained between the ends of finite chains without any special engineering of the system, although state transfer becomes slow in long chains. We discuss possible optimization methods, and find that, for any length, the best compromise between the quality and the speed of the communication is obtained in a nearly uniform chain of four spins.

arXiv:quant-ph/0603148•Physical Review A•Jul 31, 2006•58 citations

Pretty good state transfer of entangled states through quantum spin chains

Rúben Sousa, Yasser Omar

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 model, the notion of pretty good state transfer has been recently introduced as a relaxation of the constraints on fidelity. In this paper, we study the transfer of multi-qubit entangled and unentangled states through unmodulated spin chains, and we prove that it is possible to have pretty good state transfer of any multi-particle state. This significantly generalizes the previous results on single-qubit state transfer and opens the way to using uniformly coupled spin chains as short-distance quantum channels for the transfer of arbitrary states of any dimension. Our results could be tested with current technology.

arXiv:1405.1296•New Journal of Physics•Dec 2, 2014•32 citations

Interplay between speed and fidelity in off-resonant quantum-state-transfer protocols

G. M. A. Almeida

An arbitrary qubit can be transmitted through a spin chain by perturbatively coupling both communicating parties to it. These so-called weak-coupling models rely on effective Rabi oscillations between the outer spins, yielding nearly maximum fidelity while offering great resilience against disorder with the cost of having long transfer times. Considering that framework, here we address a one-dimensional nonsymmetric channel connecting two spins, one placed at each end of it. Given any pattern of nearest-neighbor coupling strengths, we obtain an analytical expression that accounts for the effective long-range interaction between them and study the interplay between transfer time and fidelity. Furthermore, we show that homogeneous channels provide the best speed-fidelity tradeoff.

arXiv:1803.10007•Physical Review A•Jul 30, 2018•21 citations

Spin-Chains as Quantum Channels for Qubit-State Transfer

Giulia Gualdi, Irene Marzoli, Paolo Tombesi

In this paper, we provide a simple strategy to optimize the performances of a spin chain as a quantum channel for state transfer.We investigate the most general conditions under which a long range interacting chain achieves the highest fidelity and the shortest transfer time. In this respect, we show that the symmetry of the spin chain plys a key role to identify the ideal system, which involves sender and receiver only, and provide numerical evidence. However, the two-spin ideal chain is unpractical due to the decrease of the coupling strength with distance. Therefore we show how to design a spin chain, which nearly approaches the optimal behaviour, while keeping the interaction strength still reasonably high.

International Conference on Quantum, Nano and Micro Technologies (ICQNM)•Feb 1, 2009•0 citations
High-fidelity quantum computation and quantum state transfer are possible in short spin chains. We exploit a system based on a dispersive qubit-boson interaction to mimic XY coupling. In this model, the usually assumed nearest-neighbor coupling is no longer valid: all the qubits are mutually coupled. We analyze the performances of our model for quantum state transfer showing how preengineered coupling rates allow for nearly optimal state transfer. We address a setup of superconducting qubits coupled to a microstrip cavity in which our analysis may be applied.
Quantum information processing requires faithful on-chip transfer of quantum states, but the couplings in solid-state systems are usually preset and not tunable, and thus in general cannot meet the special configurations needed for perfect quantum state transfer. The authors demonstrate such a perfect transfer in a chain of four superconducting qubits with nearest-neighbor coupling through $i\phantom{\rule{0}{0ex}}n$ $s\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}u$ parametric modulation, in a single step, with high fidelity (99.2%) in a short time (84 ns), thus overcoming the fixed-coupling problem. Their scheme for flexible tunability of multiqubit coupling can be easily extended to larger systems.
We study transfer of a quantum state through XXXXXX spin chains with static imperfections. We combine the two standard approaches for state transfer based on (i) modulated couplings between neighboring spins throughout the spin chain and (ii) weak coupling of the outermost spins to an unmodulated spin chain. The combined approach allows us to design spin chains with modulated couplings and localized boundary states, permitting high-fidelity state transfer in the presence of random static imperfections of the couplings. The modulated couplings are explicitly obtained from an exact algorithm using the close relation between tridiagonal matrices and orthogonal polynomials [Linear Algebr. Appl. 21, 245 (1978)]. The implemented algorithm and a graphical user interface for constructing spin chains with boundary states (spinGUIn) are provided as Supplemental Material.
We calculate the fidelity of transmission of a single qubit between distant sites on semi-infinite and finite chains of spins coupled via the magnetic dipole interaction. We show that such systems often perform better than their Heisenberg nearest-neighbor coupled counterparts, and that fidelities closely approaching unity can be attained between the ends of finite chains without any special engineering of the system, although state transfer becomes slow in long chains. We discuss possible optimization methods, and find that, for any length, the best compromise between the quality and the speed of the communication is obtained in a nearly uniform chain of four spins.
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 model, the notion of pretty good state transfer has been recently introduced as a relaxation of the constraints on fidelity. In this paper, we study the transfer of multi-qubit entangled and unentangled states through unmodulated spin chains, and we prove that it is possible to have pretty good state transfer of any multi-particle state. This significantly generalizes the previous results on single-qubit state transfer and opens the way to using uniformly coupled spin chains as short-distance quantum channels for the transfer of arbitrary states of any dimension. Our results could be tested with current technology.
An arbitrary qubit can be transmitted through a spin chain by perturbatively coupling both communicating parties to it. These so-called weak-coupling models rely on effective Rabi oscillations between the outer spins, yielding nearly maximum fidelity while offering great resilience against disorder with the cost of having long transfer times. Considering that framework, here we address a one-dimensional nonsymmetric channel connecting two spins, one placed at each end of it. Given any pattern of nearest-neighbor coupling strengths, we obtain an analytical expression that accounts for the effective long-range interaction between them and study the interplay between transfer time and fidelity. Furthermore, we show that homogeneous channels provide the best speed-fidelity tradeoff.
In this paper, we provide a simple strategy to optimize the performances of a spin chain as a quantum channel for state transfer.We investigate the most general conditions under which a long range interacting chain achieves the highest fidelity and the shortest transfer time. In this respect, we show that the symmetry of the spin chain plys a key role to identify the ideal system, which involves sender and receiver only, and provide numerical evidence. However, the two-spin ideal chain is unpractical due to the decrease of the coupling strength with distance. Therefore we show how to design a spin chain, which nearly approaches the optimal behaviour, while keeping the interaction strength still reasonably high.