Cavity quantum electrodynamics using a near-resonance two-level system: emergence of the Glauber state

Abstract

Random tunneling two-level systems (TLSs) in dielectrics have been of interest recently because they adversely affect the performance of superconducting qubits. The coupling of TLSs to qubits has allowed individual TLS characterization, which has previously been limited to TLSs within (thin) Josephson tunneling barriers made from aluminum oxide. Here we report on the measurement of an individual TLS within the capacitor of a lumped-element LC microwave resonator, which forms a cavity quantum electrodynamics (CQED) system and allows for individual TLS characterization in a different structure and material than demonstrated with qubits. Due to the reduced volume of the dielectric (80 $\mu$m${}^3$), even with a moderate dielectric thickness (250 nm), we achieve the strong coupling regime as evidenced by the vacuum Rabi splitting observed in the cavity spectrum. A TLS with a coherence time of 3.2 $\mu$s was observed in a film of silicon nitride as analyzed with a Jaynes-Cummings spectral model, which is larger than seen from superconducting qubits. As the drive power is increased, we observe an unusual but explicable set of continuous and discrete crossovers from the vacuum Rabi split transitions to the Glauber (coherent) state.

Accepted for Applied Physics Letters

References in corpus (8)

• Observation of Resonant Photon Blockade at Microwave Frequencies using Correlation Function Measurements
• High-Fidelity Readout in Circuit Quantum Electrodynamics Using the Jaynes-Cummings Nonlinearity
• Microwave Dielectric Loss at Single Photon Energies and milliKelvin Temperatures
• Measuring the temperature dependence of individual two-level systems by direct coherent control
• Quantum-to-Classical Transition in Cavity Quantum Electrodynamics
• Anomalous avoided level crossings in a Cooper-pair box spectrum
• Landau-Zener population control and dipole measurement of a two level system bath
• Evidence for hydrogen two-level systems in atomic layer deposition oxides

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• Probing hundreds of individual quantum defects in polycrystalline and amorphous alumina
• Dynamical Decoupling of Quantum Two-Level Systems by Coherent Multiple Landau-Zener Transitions
• Efficient microwave frequency conversion mediated by the vibrational motion of a silicon nitride nanobeam oscillator
• Observation of giant two-level systems in a granular superconductor
• Compact vacuum gap transmon qubits: Selective and sensitive probes for superconductor surface losses
• Possible hundredfold enhancement in the direct magnetic coupling of a single atomic spin to a circuit resonator
• Telling emissions apart in a multiphoton resonance: visualizing a conditional evolution
• Non-equilibrium Dynamics of Two-level Systems directly after Cryogenic Alternating Bias