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

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 expl...

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Bibliographic Details
Published in:Nature communications 2015-05, Vol.6 (1), p.7111-7111, Article 7111
Main Authors: Feng, M., Zhong, Y.P., Liu, T., Yan, L.L., Yang, W.L., Twamley, J., Wang, H.
Format: Article
Language:English
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639/166
639/766/119/2795
639/766/25
639/766/483/2802
Humanities and Social Sciences
multidisciplinary
Science
Science (multidisciplinary)
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Summary: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 renormalize the critical spin-field coupling strength, we have observed a four-qubit nonequilibrium quantum phase transition in a dynamical manner; that is, 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 nonequilibrium 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. Quantum phase transitions are a discontinuous change in a property of the ground state or the structure of the excited states as a system parameter traverses a critical point. Here, the authors recreate analogous effects with laboratory-achievable light-matter coupling in an on-chip superconducting circuit
ISSN:2041-1723
2041-1723
DOI:10.1038/ncomms8111