Exploring the quantum critical behaviour in a driven Tavis-Cummings circuit

Abstract

Quantum phase transitions play an important role in many-body systems and have been a research focus in conventional condensed matter physics over the past few decades. Artificial atoms, such as superconducting qubits that can be individually manipulated, provide a new paradigm of realising and exploring quantum phase transitions by engineering an on-chip quantum simulator. Here we demonstrate experimentally the quantum critical behaviour in a highly-controllable superconducting circuit, consisting of four qubits coupled to a common resonator mode. By off-resonantly driving the system to renormalise the critical spin-field coupling strength, we have observed a four-qubit non-equilibrium quantum phase transition in a dynamical manner, i.e., we sweep the critical coupling strength over time and monitor the four-qubit scaled moments for a signature of a structural change of the system's eigenstates. Our observation of the non-equilibrium quantum phase transition, which is in good agreement with the driven Tavis-Cummings theory under decoherence, offers new experimental approaches towards exploring quantum phase transition related science, such as scaling behaviours, parity breaking and long-range quantum correlations.

Main text with 3 figures

References in corpus (12)

• Beyond the Jaynes-Cummings model: circuit QED in the ultrastrong coupling regime
• Strongly Interacting Polaritons in Coupled Arrays of Cavities
• Quantum phase transitions of light
• Observation of the Bloch-Siegert Shift in a Qubit-Oscillator System in the Ultrastrong Coupling Regime
• Superconducting qubit in waveguide cavity with coherence time approaching 0.1ms
• Photon blockade induced Mott transitions and XY spin models in coupled cavity arrays
• Dressed Collective Qubit States and the Tavis-Cummings Model in Circuit QED
• Is there a no-go theorem for superradiant quantum phase transitions in cavity and circuit QED ?
• Deterministic entanglement of photons in two superconducting microwave resonators
• Quantum Phase Transition in a Resonant Level Coupled to Interacting Leads
• Demonstrating W-type Entanglement of Dicke-States in Resonant Cavity Quantum Electrodynamics
• Simulating weak localization using superconducting quantum circuits