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

Journal of Physics Conference Series

Superconducting system for adiabatic quantum computing

Valentina Corato, Tommaso Roscilde, B. Ruggiero, C. Granata, P. Silvestrini

Published Jun 1, 2006• 3 citations
Publisher

Abstract

We study the Hamiltonian of a system of inductively coupled flux qubits, which has been theoretically proposed for adiabatic quantum computation to handle NP problems. We study the evolution of a basic structure consisting of three coupled rf-SQUIDs upon tuning the external flux bias, and we show that the adiabatic nature of the evolution is guaranteed by the presence of the single-SQUID gap. We further propose a scheme and the first realization of an experimental device suitable for verifying the theoretical results.

DOI
10.1088/1742-6596/43/1/343

Related papers

Adiabatic Quantum Computation With Flux Qubits, First Experimental Results

S. H. W. van der Ploeg, A. Izmalkov, M. Grajcar +10 more

Controllable adiabatic evolution of a multi-qubit system can be used for adiabatic quantum computation (AQC). This evolution ends at a configuration where the Hamiltonian of the system encodes the solution of the problem to be solved. As a first steps towards realization of AQC we have investigated two, three and four flux qubit systems. These systems were characterized by making use of a radio-frequency method. We designed two-qubit systems with coupling energies up to several kelvins. For the three-flux-qubit systems we determined the complete ground-state flux diagram in the three dimensional flux space around the qubits common degeneracy point. We show that the system's Hamiltonian can be completely reconstructed from our measurements. Our concept for the implementation of AQC, by making use of flux qubits, is discussed.

arXiv:cond-mat/0702580•IEEE Transactions on Applied Superconductivity•Jun 1, 2007•16 citations

A scalable readout system for a superconducting adiabatic quantum optimization system

A. J. Berkley, Mark W. Johnson, P. Bunyk +7 more

We have designed, fabricated and tested an XY-addressable readout system that is specifically tailored for the reading of superconducting flux qubits in an integrated circuit that could enable adiabatic quantum optimization. In such a system, the flux qubits only need to be read at the end of an adiabatic evolution when quantum mechanical tunneling has been suppressed, thus simplifying many aspects of the readout process. The readout architecture for an $N$-qubit adiabatic quantum optimization system comprises $N$ hysteretic dc SQUIDs and $N$ rf SQUID latches controlled by $2\sqrt{N} + 2$ bias lines. The latching elements are coupled to the qubits and the dc SQUIDs are then coupled to the latching elements. This readout scheme provides two key advantages: First, the latching elements provide exceptional flux sensitivity that significantly exceeds what may be achieved by directly coupling the flux qubits to the dc SQUIDs using a practical mutual inductance. Second, the states of the latching elements are robust against the influence of ac currents generated by the switching of the hysteretic dc SQUIDs, thus allowing one to interrogate the latching elements repeatedly so as to mitigate the effects of stochastic switching of the dc SQUIDs. We demonstrate that it is possible to achieve single qubit read error rates of $<10^{-6}$ with this readout scheme. We have characterized the system-level performance of a 128-qubit readout system and have measured a readout error probability of $8\times10^{-5}$ in the presence of optimal latching element bias conditions.

arXiv:0905.0891•Superconductor Science and Technology•Sep 13, 2010•110 citations

Efficient Scheme for One-Way Quantum Computing with Radiofrequency SQUID Qubits by Adiabatic Passage

Song Ming-yu

We proposed an efficient scheme for constructing a quantum controlled phase-shift gate and generating the cluster states with rf superconducting quantum interference devices (SQUIDs) coupled to a microwave cavity through adiabatic evolution of dark eigenstates. During the operation, the spontaneous emission is suppressed since the rf SQUIDs are always in the three lowest flux states. Considering the influence from the cavity decay with achievable experimental parameters, we numerically analyze the success probability and the fidelity for generating the two-SQUID maximally entangled state and the controlled phase-shift gate by adiabatic passage.

Communications in Theoretical Physics•Nov 1, 2011•0 citations

Quantum computation and W -state generation using superconducting flux qubits coupled to a cavity without geometric and dynamical manipulation

Kehui Song, Shao-Hua Xiang, Qiong Liu +1 more

Based on superconducting quantum interference devices (SQUID's) coupled to a cavity, we propose a scheme for implementing a quantum phase-shift gate and generating a $W$ state by an adiabatic evolution of dark eigenstates, without any contributions from dynamical and geometric gates. The Sole requirement is of adiabatically increasing or decreasing Rabi frequencies of classical microwave pluses. Thus, the manipulation is robust against certain types of errors. We also analyze the experimental possibility that identical coupling can be achieved between SQUID qubits and cavity fields, and the cavity decay can be ignored in certain conditions. Based on a simple operation, our scheme may be realized in this solid-state system.

Physical Review A•Mar 29, 2007•58 citations

Adiabatic evolution of a coupled-qubit Hamiltonian

Valentina Corato, P. Silvestrini, Leo Stodolsky +1 more

We present a general method for studying coupled qubits driven by adiabatically changing external parameters. Extended calculations are provided for a two-bit Hamiltonian whose eigenstates can be used as logical states for a quantum CNOT gate. From a numerical analysis of the stationary Schr\"odinger equation we find a set of parameters suitable for representing CNOT, while from a time-dependent study the conditions for adiabatic evolution are determined. Specializing to a concrete physical system involving superconducting quantum interference devices (SQUID's), we determine reasonable parameters for experimental purposes. The dissipation for SQUID's is discussed by fitting experimental data. The low dissipation obtained supports the idea that adiabatic operations could be performed on a time scale shorter than the decoherence time.

arXiv:cond-mat/0310386•Physical review. B, Condensed matter•Dec 11, 2003•8 citations

Superconducting flux qubits: Quantum chains and tunable qubits

F. G. Paauw

This thesis presents results of theoretical and experimental work on superconducting persistent-current flux quantum bits. These qubits are promising candidates for the implementation of scalable quantum information processing. This work focuses on the study of one dimensional chains of inductively coupled flux qubits and on qubits with a tunable energy gap. Chains of flux qubits can be used as models of quantum spin chains, one of the most basic systems in many-body physics that has been extensively studied theoretically. The ability to design and tune the qubit and coupling parameters enables exploration of different phase regimes during measurements, in parameter regimes that are not accessible with magnetic materials. The study of the dynamics of quantum waves in an artificial spin chain can also be used to explore novel quantum phenomena with possible applications in quantum computing. Tunability of the minimal energy splitting (the gap) enables one to rapidly bring the flux qubit in and out of resonance with other quantum systems, including a harmonic oscillator. With tunable qubits it also becomes possible to create inter-qubit couplings of different vector nature, using magnetic fluxes. This permits the design of various interaction Hamiltonians for multiple qubit systems. These operations can be performed at the degeneracy point of the qubit, where coherence properties are optimal. Therefore the tunable flux qubit provides an attractive component for the implementation of scalable quantum computation.

•Jun 18, 2009•4 citations
We study the Hamiltonian of a system of inductively coupled flux qubits, which has been theoretically proposed for adiabatic quantum computation to handle NP problems. We study the evolution of a basic structure consisting of three coupled rf-SQUIDs upon tuning the external flux bias, and we show that the adiabatic nature of the evolution is guaranteed by the presence of the single-SQUID gap. We further propose a scheme and the first realization of an experimental device suitable for verifying the theoretical results.
Controllable adiabatic evolution of a multi-qubit system can be used for adiabatic quantum computation (AQC). This evolution ends at a configuration where the Hamiltonian of the system encodes the solution of the problem to be solved. As a first steps towards realization of AQC we have investigated two, three and four flux qubit systems. These systems were characterized by making use of a radio-frequency method. We designed two-qubit systems with coupling energies up to several kelvins. For the three-flux-qubit systems we determined the complete ground-state flux diagram in the three dimensional flux space around the qubits common degeneracy point. We show that the system's Hamiltonian can be completely reconstructed from our measurements. Our concept for the implementation of AQC, by making use of flux qubits, is discussed.
We have designed, fabricated and tested an XY-addressable readout system that is specifically tailored for the reading of superconducting flux qubits in an integrated circuit that could enable adiabatic quantum optimization. In such a system, the flux qubits only need to be read at the end of an adiabatic evolution when quantum mechanical tunneling has been suppressed, thus simplifying many aspects of the readout process. The readout architecture for an NNN-qubit adiabatic quantum optimization system comprises NNN hysteretic dc SQUIDs and NNN rf SQUID latches controlled by 2N+22\sqrt{N} + 22N​+2 bias lines. The latching elements are coupled to the qubits and the dc SQUIDs are then coupled to the latching elements. This readout scheme provides two key advantages: First, the latching elements provide exceptional flux sensitivity that significantly exceeds what may be achieved by directly coupling the flux qubits to the dc SQUIDs using a practical mutual inductance. Second, the states of the latching elements are robust against the influence of ac currents generated by the switching of the hysteretic dc SQUIDs, thus allowing one to interrogate the latching elements repeatedly so as to mitigate the effects of stochastic switching of the dc SQUIDs. We demonstrate that it is possible to achieve single qubit read error rates of <10−6<10^{-6}<10−6 with this readout scheme. We have characterized the system-level performance of a 128-qubit readout system and have measured a readout error probability of 8×10−58\times10^{-5}8×10−5 in the presence of optimal latching element bias conditions.
We proposed an efficient scheme for constructing a quantum controlled phase-shift gate and generating the cluster states with rf superconducting quantum interference devices (SQUIDs) coupled to a microwave cavity through adiabatic evolution of dark eigenstates. During the operation, the spontaneous emission is suppressed since the rf SQUIDs are always in the three lowest flux states. Considering the influence from the cavity decay with achievable experimental parameters, we numerically analyze the success probability and the fidelity for generating the two-SQUID maximally entangled state and the controlled phase-shift gate by adiabatic passage.
Based on superconducting quantum interference devices (SQUID's) coupled to a cavity, we propose a scheme for implementing a quantum phase-shift gate and generating a WWW state by an adiabatic evolution of dark eigenstates, without any contributions from dynamical and geometric gates. The Sole requirement is of adiabatically increasing or decreasing Rabi frequencies of classical microwave pluses. Thus, the manipulation is robust against certain types of errors. We also analyze the experimental possibility that identical coupling can be achieved between SQUID qubits and cavity fields, and the cavity decay can be ignored in certain conditions. Based on a simple operation, our scheme may be realized in this solid-state system.
We present a general method for studying coupled qubits driven by adiabatically changing external parameters. Extended calculations are provided for a two-bit Hamiltonian whose eigenstates can be used as logical states for a quantum CNOT gate. From a numerical analysis of the stationary Schr\"odinger equation we find a set of parameters suitable for representing CNOT, while from a time-dependent study the conditions for adiabatic evolution are determined. Specializing to a concrete physical system involving superconducting quantum interference devices (SQUID's), we determine reasonable parameters for experimental purposes. The dissipation for SQUID's is discussed by fitting experimental data. The low dissipation obtained supports the idea that adiabatic operations could be performed on a time scale shorter than the decoherence time.
This thesis presents results of theoretical and experimental work on superconducting persistent-current flux quantum bits. These qubits are promising candidates for the implementation of scalable quantum information processing. This work focuses on the study of one dimensional chains of inductively coupled flux qubits and on qubits with a tunable energy gap. Chains of flux qubits can be used as models of quantum spin chains, one of the most basic systems in many-body physics that has been extensively studied theoretically. The ability to design and tune the qubit and coupling parameters enables exploration of different phase regimes during measurements, in parameter regimes that are not accessible with magnetic materials. The study of the dynamics of quantum waves in an artificial spin chain can also be used to explore novel quantum phenomena with possible applications in quantum computing. Tunability of the minimal energy splitting (the gap) enables one to rapidly bring the flux qubit in and out of resonance with other quantum systems, including a harmonic oscillator. With tunable qubits it also becomes possible to create inter-qubit couplings of different vector nature, using magnetic fluxes. This permits the design of various interaction Hamiltonians for multiple qubit systems. These operations can be performed at the degeneracy point of the qubit, where coherence properties are optimal. Therefore the tunable flux qubit provides an attractive component for the implementation of scalable quantum computation.