Towards understanding two-level-systems in amorphous solids -- Insights from quantum circuits

Abstract

Amorphous solids show surprisingly universal behaviour at low temperatures. The prevailing wisdom is that this can be explained by the existence of two-state defects within the material. The so-called standard tunneling model has become the established framework to explain these results, yet it still leaves the central question essentially unanswered -- what are these two-level defects? This question has recently taken on a new urgency with the rise of superconducting circuits in quantum computing, circuit quantum electrodynamics, magnetometry, electrometry and metrology. Superconducting circuits made from aluminium or niobium are fundamentally limited by losses due to two-level defects within the amorphous oxide layers encasing them. On the other hand, these circuits also provide a novel and effective method for studying the very defects which limit their operation. We can now go beyond ensemble measurements and probe individual defects -- observing the quantum nature of their dynamics and studying their formation, their behaviour as a function of applied field, strain, temperature and other properties. This article reviews the plethora of recent experimental results in this area and discusses the various theoretical models which have been used to describe the observations. In doing so, it summarises the current approaches to solving this fundamentally important problem in solid-state physics.

34 pages, 7 figures, 1 table

References in corpus (159)

• Circuit Quantum Electrodynamics: Coherent Coupling of a Single Photon to a Cooper Pair Box
• Cavity quantum electrodynamics for superconducting electrical circuits: an architecture for quantum computation
• Coherent control of macroscopic quantum states in a single-Cooper-pair box
• Logic gates at the surface code threshold: Superconducting qubits poised for fault-tolerant quantum computing
• Observation of high coherence in Josephson junction qubits measured in a three-dimensional circuit QED architecture
• Decoherence in Josephson Qubits from Dielectric Loss
• Coherent Josephson qubit suitable for scalable quantum integrated circuits
• Hybrid quantum systems based on magnonics
• Josephson-Junction Qubits with Controlled Couplings
• Coherent quantum state storage and transfer between two phase qubits via a resonant cavity
• Decoherence in a superconducting quantum bit circuit
• 1/f noise: implications for solid-state quantum information
• Superconducting qubit in waveguide cavity with coherence time approaching 0.1ms
• Suppressing Charge Noise Decoherence in Superconducting Charge Qubits
• Planar Superconducting Resonators with Internal Quality Factors above One Million
• Phase preserving amplification near the quantum limit with a Josephson Ring Modulator
• Decoherence in Josephson Qubits from Junction Resonances
• Ion-trap measurements of electric-field noise near surfaces
• Experimental evidence for a surface distribution of two-level systems in superconducting lithographed microwave resonators
• Fluctuations of Energy-Relaxation Times in Superconducting Qubits
• Decoherence benchmarking of superconducting qubits
• Implementing the Quantum von Neumann Architecture with Superconducting Circuits
• Dephasing of a superconducting qubit induced by photon noise
• Quantum noise in the Josephson charge qubit
• High Kinetic Inductance Superconducting Nanowire Resonators for Circuit QED in a Magnetic Field
• Microwave Dielectric Loss at Single Photon Energies and milliKelvin Temperatures
• Improved superconducting qubit coherence using titanium nitride
• Relaxation and frequency shifts induced by quasiparticles in superconducting qubits
• Observation of quantum oscillations between a Josephson phase qubit and a microscopic resonator using fast readout
• Reducing intrinsic loss in superconducting resonators by surface treatment and deep etching of silicon substrates
• State tomography of capacitively shunted phase qubits with high fidelity
• Study of loss in superconducting coplanar waveguide resonators
• Surface loss simulations of superconducting coplanar waveguide resonators
• Model for l/f Flux Noise in SQUIDs and Qubits
• Low Loss Superconducting Titanium Nitride Coplanar Waveguide Resonators
• Noise Properties of Superconducting Coplanar Waveguide Microwave Resonators
• Optomechanical sideband cooling of a micromechanical oscillator close to the quantum ground state
• Low- and high-frequency noise from coherent two-level systems
• Dephasing of a superconducting flux qubit
• Observation of directly interacting coherent two-level systems in a solid
• Decoherence in Josephson-junction qubits due to critical current fluctuations
• Evidence for interacting two-level systems from the 1/f noise of a superconducting resonator
• Analysis and mitigation of interface losses in trenched superconducting coplanar waveguide resonators
• Improving the Coherence Time of Superconducting Coplanar Resonators
• Magnetism in SQUIDs at Millikelvin Temperatures
• A semi-empirical model for two-level system noise in superconducting microresonators
• Origin and Suppression of $1/f$ Magnetic Flux Noise
• Interacting two-level defects as sources of fluctuating high-frequency noise in superconducting circuits
• Minimal resonator loss for circuit quantum electrodynamics
• Microscopic origin of low frequency flux noise in Josephson circuits
• Fabrication and Characterization of Aluminum Airbridges for Superconducting Microwave Circuits
• Observation of classical-quantum crossover of 1/f flux noise and its paramagnetic temperature dependence
• Surface acoustic wave resonators in the quantum regime
• Characterization and reduction of microfabrication-induced decoherence in superconducting quantum circuits
• Quantum two-level systems in Josephson junctions as naturally formed qubits
• Lifetime and Coherence of Two-Level Defects in a Josephson Junction
• Measurement-induced qubit state mixing in circuit QED from up-converted dephasing noise
• Generalized Tunneling Model for TLS in amorphous materials and its predictions for their dephasing and the noise in superconducting microresonators
• Contribution of dielectrics to frequency and noise of NbTiN superconducting resonators
• Localization of Metal-Induced Gap States at the Metal-Insulator Interface:Origin of Flux Noise in SQUIDs and Superconducting Qubits
• Investigating surface loss effects in superconducting transmon qubits
• Suppression of 1/f noise in solid state quantum devices by surface spin desorption
• Losses in coplanar waveguide resonators at millikelvin temperatures
• Qubit metrology of ultralow phase noise using randomized benchmarking
• Measuring the temperature dependence of individual two-level systems by direct coherent control
• Etch Induced Microwave Losses in Titanium Nitride Superconducting Resonators
• Direct identification of dilute surface spins on Al${}_2$O${}_3$: Origin of flux noise in quantum circuits
• Fabrication of stable and reproducible sub-micron tunnel junctions
• Decoherence spectroscopy with individual two-level tunneling defects
• Extremely Low-Loss Acoustic Phonons in a Quartz Bulk Acoustic Wave Resonator at Millikelvin Temperature
• Bulk and surface loss in superconducting transmon qubits
• Flux Qubits and Readout Device with Two Independent Flux Lines
• Oxygen stoichiometry and instability in aluminium oxide tunnel barrier layers
• Low-loss superconducting resonant circuits using vacuum-gap-based microwave components
• Bulk and Surface Tunneling Hydrogen Defects in Alumina
• Quantum two level systems and Kondo-like traps as possible sources of decoherence in superconducting qubits
• On the properties of superconducting planar resonators at mK temperatures
• Projected dipole moments of individual two-level defects extracted using circuit quantum electrodynamics
• Spin-like susceptibility of metallic and insulating thin films at low temperature
• Analysis of high quality superconducting resonators: consequences for TLS properties in amorphous oxides
• Internal loss of superconducting resonators induced by interacting two level systems
• Temperature Dependence of the Frequency and Noise of Superconducting Coplanar Waveguide Resonators
• High Q-factor Sapphire Whispering Gallery Mode Microwave Resonator at Single Photon Energies and milli-Kelvin Temperatures
• The "Tunneling Two-Level Systems" Model of the Low-Temperature Properties of Glasses: Are "Smoking-Gun" Tests Possible?
• Models of environment and T_1 relaxation in Josephson Charge Qubits
• Quantum Friction in Nanomechanical Oscillators at Millikelvin Temperatures
• Loss mechanisms in superconducting thin film microwave resonators
• Candidate source of flux noise in SQUIDs: adsorbed oxygen molecules
• Polaronic model of Two Level Systems in amorphous solids
• Fluctuations From Edge Defects in Superconducting Resonators
• Decoherence of a Josephson qubit due to coupling to two level systems
• Coherence in a transmon qubit with epitaxial tunnel junctions
• Dissipation due to tunneling two-level systems in gold nanomechanical resonators
• One- and two-photon spectroscopy of a flux qubit coupled to a microscopic defect
• Damping in high-frequency metallic nanomechanical resonators
• Reduced frequency noise in superconducting resonators
• Complete stabilization and improvement of the characteristics of tunnel junctions by thermal annealing
• Decoherence of a qubit due to a quantum fluctuator or to a classical telegraph noise
• Anomalous avoided level crossings in a Cooper-pair box spectrum
• Microscopic Model of Critical Current Noise in Josephson Junctions
• What is moving in silica at 1 K? A computer study of the low-temperature anomalies
• Pure dephasing in flux qubits due to flux noise with spectral density scaling as $1/f^{\alpha }$
• Quantum decoherence of a charge qubit in a spin-fermion model
• Dissipation due to two-level systems in nano-mechanical devices
• Delocalised oxygen as the origin of two-level defects in Josephson junctions
• Quantitative evaluation of defect-models in superconducting phase qubits
• Noise and loss of superconducting aluminium resonators at single photon energies
• Suspending superconducting qubits by silicon micromachining
• Universal Sound Absorption in Amorphous Solids: A Theory of Elastically Coupled Generic Blocks
• Pound-locking for characterization of superconducting microresonators
• Evidence of universality in the dynamical response of micromechanical diamond resonators at millikelvin temperatures
• Rabi spectroscopy of a strongly driven qubit-fluctuator system
• Quantum Friction of Micromechanical Resonators at Low Temperatures
• Probing individual tunneling fluctuators with coherently controlled tunneling systems
• Multi-photon spectroscopy of a hybrid quantum system
• Microscopic origin of critical current fluctuations in large, small and ultra-small area Josephson junctions
• Low temperature universality in disordered solids
• Signatures of two-level defects in the temperature-dependent damping of nanomechanical silicon nitride resonators
• Strongly quadrature-dependent noise in superconducting micro-resonators measured at the vacuum-noise limit
• Relaxation of Josephson qubits due to strong coupling to two-level systems
• Landau-Zener population control and dipole measurement of a two level system bath
• Multi-level Spectroscopy of Two-Level Systems Coupled to a dc SQUID Phase Qubit
• Electronic Decoherence of Two-Level Systems in a Josephson Junction
• Quantum dynamics in a camel-back potential of a dc SQUID
• Identification of structural motifs as tunneling two-level systems in amorphous alumina at low temperatures
• Long-lived, radiation-suppressed superconducting quantum bit in a planar geometry
• Microscopic model of critical current noise in Josephson-junction qubits: Subgap resonances and Andreev bound states
• Revealing the nonlinear response of a tunneling two-level system ensemble using coupled modes
• Low frequency resistance and critical current fluctuations in Al-based Josephson junctions
• Low temperature 1/f noise in microwave dielectric constant of amorphous dielectrics in Josephson qubits
• Transmission-line resonators for the study of individual two-level tunneling systems
• Slow noise processes in superconducting resonators
• A Josephson junction defect spectrometer for measuring two-level systems
• Why Study Noise due to Two Level Systems: A Suggestion for Experimentalists
• Non-equilibrium probing of two-level charge fluctuators using the step response of a single electron transistor
• Thermal properties of charge noise sources
• Dielectric losses in multi-layer Josephson junction qubits
• Vacuum-Gap Capacitors for Low-Loss Superconducting Resonant Circuits
• Flux $1/f^{\alpha }$ noise in 2D Heisenberg spin glasses: effects of weak anisotropic interactions
• Constructing ab initio models of ultra-thin Al-AlOx-Al barriers
• Identification of strong and weak interacting two level systems in KBr:CN
• Spectroscopy of a Cooper-Pair Box Coupled to a Two-Level System Via Charge and Critical Current
• Non-homogeneity of the density of states of tunneling two-level systems at low energies
• Decoherence of a quantum two-level system by spectral diffusion
• Characterization of low-temperature microwave loss of thin aluminum oxide formed by plasma oxidation
• Atomic delocalisation as a microscopic origin of two-level defects in Josephson junctions
• Coherent Josephson phase qubit with a single crystal silicon capacitor
• Entanglement dynamics of a superconducting phase qubit coupled to a two-level system
• Electrodynamics of Amorphous Media at Low Temperatures
• A superconducting qubit as a quantum transformer routing entanglement between a microscopic quantum memory and a macroscopic resonator
• Entangling microscopic defects via a macroscopic quantum shuttle
• Sub-micrometer epitaxial Josephson junctions for quantum circuits
• Quasiparticle poisoning and Josephson current fluctuations induced by Kondo impurities
• Theory of nonlinear microwave absorption by interacting two-level systems
• Nonuniversality and strongly interacting two-level systems in glasses at low temperatures
• Reduced leakage current in Josephson tunnel junctions with codeposited barriers
• Coupling mechanism between microscopic two-level system and superconducting qubits
• Structural evolution of Re (0001) thin films grown on Nb (110) surfaces by molecular beam epitaxy
• Squeezed noise due to two-level system defects in superconducting resonator circuits

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• Spectroscopy and Coherent Control of Two-Level System Defect Ensembles Using a Broadband 3D Waveguide
• Effects of the thin-film thickness on superconducting NbTi microwave resonators for on-chip cryogenic thermometry
• Time-resolved spectral diffusion of a multimode mechanical memory
• A fermion phenomenology of low-temperature strongly-noncrystalline solids