Qubit Decoherence in Two-Photon Resonators Linked to Wigner Function Via Real-Time Instantons
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The behaviour of qubits, the fundamental building blocks of quantum computers, remains a central challenge in physics, and understanding how these systems lose quantum information through decoherence is paramount. Researchers, including V. Yu. Mylnikov of the Ioffe Institute, S. O. Potashin, and Alex Kamenev from the University of Minnesota, now present a new theoretical framework for analysing decoherence in nonlinear resonators used to create bosonic qubits. Their work reveals a fundamental connection between the steady-state behaviour of these qubits and the dynamic processes governing their decay, offering a way to predict and control decoherence rates. By linking the system’s phase-space description with the instanton trajectories that describe transitions between stable states, the team provides a coherent understanding of bistability, metastability, and decoherence, with significant implications for the development of more robust quantum information processing technologies. Qubit Decoherence in Driven Dissipative Cavities Scientists investigate the quantum dynamics of a single cavity interacting with light and experiencing energy loss, alongside a qubit, to understand how these interactions cause decoherence, the loss of quantum information.
This research explores how driving the cavity with light, combined with energy dissipation, affects the quantum state of the system.
The team focuses on understanding the behaviour of ‘instantons’, solutions that describe transitions between different quantum states, and uses the Wigner function to characterise the quantum nature of the cavity. Their approach involves a theoretical treatment using quantum Langevin equations and influence functional formalism. By analysing the instanton trajectories and the shape of the Wigner function, researchers gain insights into the mechanisms causing qubit decoherence and the conditions under which quantum coherence can be maintained. The study demonstrates that energy loss through two-photon processes introduces unique decoherence pathways, differing from those caused by single-photon processes. Furthermore, analysis of the Wigner function reveals non-classical features in the cavity’s quantum state, even with strong energy loss, suggesting potential applications in quantum information processing and other areas requiring robust quantum coherence.
Nonlinear Quantum Fluctuations in Superconducting Qubits This research presents a comprehensive investigation into quantum optics, nonlinear oscillators, and the theory of fluctuations, with a strong focus on applications to superconducting qubits and related technologies. The work builds upon established theoretical frameworks, including the Keldysh formalism, Fokker-Planck equations, and instanton methods, to analyse the behaviour of superconducting qubits and other quantum devices. Key areas covered include understanding the behaviour of quantum systems driven by external forces and exhibiting nonlinear responses, modelling and mitigating the effects of fluctuations on these systems. The research is motivated by the challenges and opportunities presented by superconducting qubits, including decoherence, noise sensitivity, and the need for improved control. The ultimate goal is to develop theoretical tools and insights that can be used to design and optimise quantum devices for various applications. This is a valuable resource for researchers working on the theoretical and experimental aspects of quantum computing and related fields. Decoherence and Metastable States in Driven Cavities This work presents a theoretical framework for understanding the behaviour of a single cavity subjected to light and energy loss. Researchers successfully developed an effective phase-space potential, revealing two attracting states within the system, which, despite being unstable, are influenced by inherent fluctuations. By employing the Keldysh real-time path integral formalism, the team established a direct connection between the instanton trajectory governing transitions between these states and the Wigner representation, effectively unifying the description of steady-state properties with dynamical activation processes. Furthermore, the study derives an analytical expression for the system’s decoherence rate, providing valuable insight into how quantum information is lost. This achievement offers a coherent understanding of instability, metastability, and decoherence in driven-dissipative nonlinear resonators, with direct implications for the development of qubits and advanced quantum information processing technologies. 👉 More information 🗞 Qubit decoherence in dissipative two-photon resonator: real-time instantons and Wigner function 🧠 ArXiv: https://arxiv.org/abs/2512.10921 Tags: Rohail T. As a quantum scientist exploring the frontiers of physics and technology. My work focuses on uncovering how quantum mechanics, computing, and emerging technologies are transforming our understanding of reality. I share research-driven insights that make complex ideas in quantum science clear, engaging, and relevant to the modern world. Latest Posts by Rohail T.: Surface Acoustic Waves Drive Valley Current Generation in Intervalley Coherent States, Enabling Exploration of Valley-Gauge Symmetry Breaking December 12, 2025 Kagome Superconductors Exhibit Incipient Charge Density Wave Order and Hidden Quantum Critical Point December 12, 2025 Quantum Algorithm Estimates Ollivier-Ricci Curvature with Exponential Speedup on Graph Inputs December 12, 2025