Distinguishing coherent and thermal photon noise in a circuit QED system

Abstract

In the cavity-QED architecture, photon number fluctuations from residual cavity photons cause qubit dephasing due to the AC Stark effect. These unwanted photons originate from a variety of sources, such as thermal radiation, leftover measurement photons, and crosstalk. Using a capacitively-shunted flux qubit coupled to a transmission line cavity, we demonstrate a method that identifies and distinguishes coherent and thermal photons based on noise-spectral reconstruction from time-domain spin-locking relaxometry. Using these measurements, we attribute the limiting dephasing source in our system to thermal photons, rather than coherent photons. By improving the cryogenic attenuation on lines leading to the cavity, we successfully suppress residual thermal photons and achieve $T_1$-limited spin-echo decay time. The spin-locking noise spectroscopy technique can readily be applied to other qubit modalities for identifying general asymmetric non-classical noise spectra.

References in corpus (17)

• Coupling Superconducting Qubits via a Cavity Bus
• Dynamical decoupling and noise spectroscopy with a superconducting flux qubit
• Resolving photon number states in a superconducting circuit
• 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
• Controlling the spontaneous emission of a superconducting transmon qubit
• AC-Stark Shift and Dephasing of a Superconducting Qubit Strongly Coupled to a Cavity Field
• Qubit-photon interactions in a cavity: Measurement induced dephasing and number splitting
• 1/f Flux Noise in Josephson Phase Qubits
• Thermal and Residual Excited-State Population in a 3D Transmon Qubit
• Photon Shot Noise Dephasing in the Strong-Dispersive Limit of Circuit QED
• Suppressing relaxation in superconducting qubits by quasiparticle pumping
• Observation of classical-quantum crossover of 1/f flux noise and its paramagnetic temperature dependence
• Multiqubit Spectroscopy of Gaussian Quantum Noise
• Radio-frequency magnetometry using a single electron spin
• Photon Statistics of Propagating Thermal Microwaves
• Qubits as Spectrometers of Quantum Noise

Cited by in corpus (58)

• A Quantum Engineer's Guide to Superconducting Qubits
• Perspectives of quantum annealing: Methods and implementations
• High-Fidelity, Frequency-Flexible Two-Qubit Fluxonium Gates with a Transmon Coupler
• Cavity Attenuators for Superconducting Qubits
• Non-Gaussian noise spectroscopy with a superconducting qubit sensor
• Two-qubit spectroscopy of spatiotemporally correlated quantum noise in superconducting qubits
• Scalable High-Performance Fluxonium Quantum Processor
• Large collective Lamb shift of two distant superconducting artificial atoms
• Erasure qubits: Overcoming the $T_1$ limit in superconducting circuits
• Long-distance transmon coupler with CZ gate fidelity above $99.8\%$
• Fast logic with slow qubits: microwave-activated controlled-Z gate on low-frequency fluxoniums
• Enhanced precision bound of low-temperature quantum thermometry via dynamical control
• Two-qubit logic between distant spins in silicon
• Overcoming I/O bottleneck in superconducting quantum computing: multiplexed qubit control with ultra-low-power, base-temperature cryo-CMOS multiplexer
• Error per single-qubit gate below $10^{-4}$ in a superconducting qubit
• High-Fidelity Measurement of a Superconducting Qubit using an On-Chip Microwave Photon Counter
• A long-lived capacitively shunted flux qubit embedded in a 3D cavity
• Universal non-adiabatic control of small-gap superconducting qubits
• Multi-level Quantum Noise Spectroscopy
• Simultaneous spectral estimation of dephasing and amplitude noise on a qubit sensor via optimally band-limited control
• Quantum Microwave Radiometry with a Superconducting Qubit
• Efficient and Low-Backaction Quantum Measurement Using a Chip-Scale Detector
• Photon-noise-tolerant dispersive readout of a superconducting qubit using a nonlinear Purcell filter
• Primary thermometry of propagating microwaves in the quantum regime
• Engineering the microwave to infrared noise photon flux for superconducting quantum systems
• Extending comb-based spectral estimation to multiaxis quantum noise
• Fast multiplexed superconducting qubit readout with intrinsic Purcell filtering
• Design of an on-chip superconducting microwave circulator with octave bandwidth
• Efficient quantum error correction of dephasing induced by a common fluctuator
• Microwave calibration of qubit drive line components at millikelvin temperatures
• Strong parametric dispersive shifts in a statically decoupled multi-qubit cavity QED system
• Integrating superfluids with superconducting qubit systems
• Landau-Zener-Stückelberg Interferometry in dissipative Circuit Quantum Electrodynamics
• On-demand driven dissipation for cavity reset and cooling
• Ramsey Interferometry in Correlated Quantum Noise Environments
• Driven-state relaxation of a coupled qubit-defect system in spin-locking measurements
• Fault-tolerant quantum architectures based on erasure qubits
• SPAM-Robust Multi-axis Quantum Noise Spectroscopy in Temporally Correlated Environments
• SchWARMA: A model-based approach for time-correlated noise in quantum circuits
• Frequency estimation under non-Markovian spatially correlated quantum noise: Restoring superclassical precision scaling
• Efficient decoupling of a non-linear qubit mode from its environment
• The superconducting circuit companion -- an introduction with worked examples
• Parametric multi-element coupling architecture for coherent and dissipative control of superconducting qubits
• Robust gates with spin-locked superconducting qubits
• Limitations to Dynamical Error Suppression and Gate-Error Virtualization from Temporally Correlated Nonclassical Noise
• Control of transition frequency of a superconducting flux qubit by longitudinal coupling to the photon number degree of freedom in a resonator
• In situ mixer calibration for superconducting quantum circuits
• Sub-Harmonic Control of a Fluxonium Qubit via a Purcell-Protected Flux Line
• Decoherence of a tunable capacitively shunted flux qubit
• New Technologies for Discovery
• Characterization of multi-level dynamics and decoherence in a high-anharmonicity capacitively shunted flux circuit
• Intrinsic and induced quantum quenches for enhancing qubit-based quantum noise spectroscopy
• Coherence-Mediated Quantum Thermometry in a Hybrid Circuit-QED Architecture
• Optimizing the frequency positioning of tunable couplers in a circuit QED processor to mitigate spectator effects on quantum operations
• Non-destructive optical readout of a superconducting qubit
• Systematic Construction of Time-Dependent Hamiltonians for Microwave-Driven Josephson Circuits
• Routing single photons with quantum emitters coupled to nanostructures
• Mediated interactions beyond the nearest neighbor in an array of superconducting qubits