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arXiv · 2604.00802

Unitary Encoding of Thermal States via Thermofield Dynamics on Quantum Computers

G. X. A. Petronilo·M. R. Araújo·A. B. M. Souza·Clebson Cruz
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Abstract

Quantum computing has attracted the attention of the scientific community in the past few decades. However, despite some relevant advantages, near-term quantum devices remain severely limited by thermal effects, which induce decoherence and restrict coherent control at finite temperature. In this regard, this work reports a gate-based quantum algorithm that prepares the finite-temperature vacuum of Thermofield Dynamics (TFD) and tracks its real-time evolution. The circuit depth scales linearly with system size and requires only single-qubit rotations and nearest-neighbor CNOT gates, making it NISQ-friendly. We benchmark the protocol on the PennyLane simulator: magnetization of a spin-$1/2$ particle in a magnetic field agrees with the exact result $M(β)=\tanh(βω/2)$ to machine precision, and the coherent precession acquires a temperature-dependent damping that quantitatively matches the analytical TFD prediction. Our work provides a ready-to-deploy toolbox for thermal quantum simulations and opens a route to study dissipative phase transitions, quantum thermodynamics and thermal machine-learning models on near-term devices.

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G. X. A. Petronilo, M. R. Araújo, A. B. M. Souza, Clebson Cruz. 2026-04-01. Unitary Encoding of Thermal States via Thermofield Dynamics on Quantum Computers. https://arxiv.org/abs/2604.00802

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