Four-qubit device with mixed couplings

Abstract

We present the first experimental results on a device with more than two superconducting qubits. The circuit consists of four three-junction flux qubits, with simultaneous ferro- and antiferromagnetic coupling implemented using shared Josephson junctions. Its response, which is dominated by the ground state, is characterized using low-frequency impedance measurement with a superconducting tank circuit coupled to the qubits. The results are found to be in excellent agreement with the quantum-mechanical predictions.

REVTeX 4, 5pp., 7 EPS figure files. N.B.: "Alec" is my first, and "Maassen van den Brink" my family name. v2: final published version, with changed title, different sample micrograph, and several clarifications

References in corpus (16)

• Efficient classical simulation of slightly entangled quantum computations
• Coherent control of macroscopic quantum states in a single-Cooper-pair box
• Manipulating the Quantum State of an Electrical Circuit
• Coherent Quantum Dynamics of a Superconducting Flux Qubit
• A Superconducting Persistent Current Qubit
• Demonstration of conditional gate operation using superconducting charge qubits
• Dephasing of a superconducting qubit induced by photon noise
• Evidence for entangled states of two coupled flux qubits
• Continuous Monitoring of Rabi Oscillations in a Josephson Flux Qubit
• Nondestructive readout for a superconducting flux qubit
• Fast two-bit operations in inductively coupled flux qubits
• Low-frequency measurement of the tunneling amplitude in a flux qubit
• Low-frequency characterization of quantum tunneling in flux qubits
• Direct Josephson coupling between superconducting flux qubits
• Possible implementation of adiabatic quantum algorithm with superconducting flux qubits
• Hamiltonian for coupled flux qubits

Cited by in corpus (52)

• Quantum information processing with superconducting circuits: a review
• Natural and artificial atoms for quantum computation
• Coherent quantum state storage and transfer between two phase qubits via a resonant cavity
• Experimental Investigation of an Eight Qubit Unit Cell in a Superconducting Optimization Processor
• Low-decoherence flux qubit
• Arbitrary accuracy iterative phase estimation algorithm as a two qubit benchmark
• Controllable coupling of superconducting flux qubits
• Experimental Demonstration of a Robust and Scalable Flux Qubit
• Dissipative Landau-Zener transitions of a qubit: bath-specific and universal behavior
• Quantum computing by optical control of electron spins
• Scalable superconducting qubit circuits using dressed states
• Scalable quantum computation via local control of only two qubits
• Consistency of ground state and spectroscopic measurements on flux qubits
• Robustness of spin-coupling distributions for perfect quantum state transfer
• Two-dimensional cavity grid for scalable quantum computation with superconducting circuits
• Generation of squeezed states of microwave radiation in a superconducting resonant circuit
• Interqubit coupling mediated by a high-excitation-energy quantum object
• Effective Floquet-Gibbs states for dissipative quantum systems
• Quantum refrigerator driven by current noise
• Coherent output of photons from coupled superconducting transmission line resonators controlled by charge qubits
• Quantum parallelism as a tool for ensemble spin dynamics calculations
• Coupling superconducting flux qubits at optimal point via dynamic decoupling with the quantum bus
• Observing pure effects of counter-rotating terms without ultrastrong coupling: A single photon can simultaneously excite two qubits
• Calibration of flux crosstalk in large-scale flux-tunable superconducting quantum circuits
• Probing Quantum Phase Transition in Macroscopic Qubit Array via circuit QED architecture
• Circuit QED with a Flux Qubit Strongly Coupled to a Coplanar Transmission Line Resonator
• Spectroscopy of three strongly coupled flux qubits
• Ideal Quantum Nondemolition Readout of a Flux Qubit Without Purcell Limitations
• Spectroscopy of superconducting charge qubits coupled by a Josephson inductance
• Characterization of an entangled system of two superconducting qubits using a multiplexed capacitance readout
• Parametric amplification by coupled flux qubits
• Decoherence as attenuation of mesoscopic echoes in a spin-chain channel
• Enhanced-Fidelity Ultrafast Geometric Quantum Computation Using Strong Classical Drives
• Robust creation of entangled states of two coupled flux qubits via dynamic control of the transition frequencies
• Simulating long-distance entanglement in quantum spin chains by superconducting flux qubits
• Measurement of the ground-state flux diagram of three coupled qubits as a first step towards the demonstration of adiabatic quantum computation
• Two-dimensional Ising model with competing interactions and its application to clusters and arrays of $\pi$-rings and adiabatic quantum computing
• Stationary entanglement in strongly coupled qubits
• Pseudo-Rabi oscillations in superconducting flux qubits in the classical regime
• Controllable Coupling in Phase-Coupled Flux Qubits
• Entanglement and Bell States in Superconducting Flux Qubits
• Quantum theory of the low-frequency linear susceptibility of interferometer-type superconducting qubits
• Normal modes of a superconducting transmission-line resonator with embedded lumped element circuit components
• Robust quantum sensing with strongly interacting probe systems
• Sequential nonideal measurements of quantum oscillators: Statistical characterization with and without environmental coupling
• Implementing Genuine Multi-Qubit Entanglement of Two-Level-System Inside a Superconducting Phase Qubit
• Macroscopic Many-Qubit Interactions in Superconducting Flux Qubits
• Effects of Strong Capacitive Coupling Between Meta-Atoms in rf SQUID Metamaterials
• Optimal effective current operator for flux qubit accounting for inductive effects
• Modeling Three and Four Coupled Phase Qubits
• Energies and Entanglement in Multiply-coupled Phase Qubit Systems
• Efficient steady state entanglement generation in strongly driven coupled qubits