Unitary Encoding of Thermal States via Thermofield Dynamics on Quantum Computers

• URL: http://arxiv.org/abs/2604.00802v1
• Date: Wed, 01 Apr 2026 12:07:30 GMT
• Title: Unitary Encoding of Thermal States via Thermofield Dynamics on Quantum Computers
• Abstract summary: This work reports a gate-based quantum algorithm that prepares the finite-temperature vacuum of Thermofield Dynamics.<n>The circuit depth scales linearly with system size and requires only single-qubit rotations and nearest-neighbor CNOT gates.<n>Our work provides a ready-to-deploy toolbox for thermal quantum simulations and opens a route to study dissipative phase transitions.
• Score: 0.0
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• 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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