Tunable-Cavity QED with Phase Qubits

Abstract

We describe a tunable-cavity QED architecture with an rf SQUID phase qubit inductively coupled to a single-mode, resonant cavity with a tunable frequency that allows for both microwave readout of tunneling and dispersive measurements of the qubit. Dispersive measurement is well characterized by a three-level model, strongly dependent on qubit anharmonicity, qubit-cavity coupling and detuning. A tunable cavity frequency provides a way to strongly vary both the qubit-cavity detuning and coupling strength, which can reduce Purcell losses, cavity-induced dephasing of the qubit, and residual bus coupling for a system with multiple qubits. With our qubit-cavity system, we show that dynamic control over the cavity frequency enables one to avoid Purcell losses during coherent qubit evolutions and optimize state readout during qubit measurements. The maximum qubit decay time $T_1$ = 1.5 $\mu$s is found to be limited by surface dielectric losses from a design geometry similar to planar transmon qubits.

17 pages, 10 figures

References in corpus (26)

• Charge insensitive qubit design derived from the Cooper pair box
• Coupling Superconducting Qubits via a Cavity Bus
• Demonstration of Two-Qubit Algorithms with a Superconducting Quantum Processor
• Coherent quantum state storage and transfer between two phase qubits via a resonant cavity
• Superconducting qubit in waveguide cavity with coherence time approaching 0.1ms
• Approaching Unit Visibility for Control of a Superconducting Qubit with Dispersive Readout
• Controlling the spontaneous emission of a superconducting transmon qubit
• Quantum feedback control of a superconducting qubit: Persistent Rabi oscillations
• Complete universal quantum gate set approaching fault-tolerant thresholds with superconducting qubits
• Observation of quantum jumps in a superconducting artificial atom
• Dispersive regime of circuit QED: photon-dependent qubit dephasing and relaxation rates
• Quantum trajectory approach to circuit QED: Quantum jumps and the Zeno effect
• Single-shot qubit readout in circuit Quantum Electrodynamics
• Single-shot qubit readout in circuit Quantum Electrodynamics
• High-Fidelity Readout in Circuit Quantum Electrodynamics Using the Jaynes-Cummings Nonlinearity
• Fast Reset and Suppressing Spontaneous Emission of a Superconducting Qubit
• Implementation of low-loss superinductances for quantum circuits
• Feedback control of a solid-state qubit using high-fidelity projective measurement
• Two-Qubit State Tomography using a Joint Dispersive Read-Out
• Tunable coupling in circuit quantum electrodynamics with a superconducting V-system
• Photon Shot Noise Dephasing in the Strong-Dispersive Limit of Circuit QED
• Improved Superconducting Qubit Readout by Qubit-Induced Nonlinearities
• Measurement-induced qubit state mixing in circuit QED from up-converted dephasing noise
• Improving the Quality Factor of Microwave Compact Resonators by Optimizing their Geometrical Parameters
• Low-frequency measurement of the tunneling amplitude in a flux qubit
• Improved qubit bifurcation readout in the straddling regime of circuit QED

Cited by in corpus (4)

• Robust quantum state transfer using tunable couplers
• Engineering adiabaticity at an avoided crossing with optimal control
• Simulating long-distance entanglement in quantum spin chains by superconducting flux qubits
• Simulating dynamical quantum Hall effect with superconducting qubits