Double-bracket quantum algorithms for thermal state preparation

• URL: http://arxiv.org/abs/2606.05947v1
• Date: Thu, 04 Jun 2026 09:46:43 GMT
• Title: Double-bracket quantum algorithms for thermal state preparation
• Abstract summary: We implement imaginary-time evolution on thermofield double states via double-bracket quantum algorithms.<n>We show that the complexity of the poly DB-TFD algorithm scales exponentially with a broad practical regime.<n>These results establish DB-TFD as a promising route for thermal state preparation in the near-term and early-fault-tolerant regimes.
• Score: 0.0
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: We propose quantum algorithms for preparing thermal states via the simulation of the thermofield double states. The key idea is to leverage double-bracket quantum algorithms to implement imaginary-time evolution on thermofield double states, whose reduced state realizes the Gibbs state. Our method, termed double-bracket thermofield double (DB-TFD), introduces two variants. The first, the vanilla DB-TFD algorithm, directly implements imaginary-time evolution using double-bracket quantum imaginary-time evolution. The second, poly DB-TFD, employs double-bracket quantum signal processing to approximate the imaginary-time evolution operator via a polynomial transformation. We demonstrate that the complexity of the poly DB-TFD algorithm scales exponentially with the inverse temperature in a broad practical regime. This scaling is consistent with existing methods, and numerical simulations support the corresponding theoretical bound. We further demonstrate the utility of DB-TFD in quantum Boltzmann machines for generative modeling, achieving improved performance compared with variational imaginary-time evolution approaches. These results establish DB-TFD as a promising route for thermal state preparation in the near-term and early-fault-tolerant regimes.

Related papers

• Preparing a Thermofield Double State with Feedback Quantum Algorithms [0.0]
  Ground state preparation of correlated thermal states is a fundamental prerequisite for simulating quantum gravity models and many-body thermodynamics on quantum processors.<n>In this work, we investigate the ground state preparation of the Two Coupled Sachdev-Ye-Kitaev model, known as the Maldacena-Qi model, which is dual to a traversable wormhole in $AdS$.<n>We propose the hybrid ITETR-FALQON protocol, which integrates the imaginary-time evolution present in imaginary-time-enhanced FALQON with the time-rescaling mechanism.
  arXiv  Detail & Related papers  (2026-07-02T03:25:37Z)
• Double-Bracket Algorithmic Cooling [0.5417521241272645]
  We introduce double-bracket algorithmic cooling (DBAC), a protocol that systematically suppresses quantum coherence of pure states.<n>Our work demonstrates that dynamic quantum algorithms are a promising route toward new protocols for foundational tasks in quantum thermodynamics.
  arXiv  Detail & Related papers  (2025-09-30T21:46:28Z)
• Double-bracket quantum algorithms for quantum imaginary-time evolution [0.0]
  We prove that our Double-Bracket Quantum Imaginary-Time Evolution (DB-QITE) algorithm inherits the cooling guarantees of imaginary-time evolution.<n>We provide gate counts for DB-QITE through numerical simulations in Qrisp.
  arXiv  Detail & Related papers  (2024-12-05T19:00:09Z)
• Quantum real-time evolution using tensor renormalization group methods [0.0]
  We introduce an approach for approximate real-time evolution of quantum systems using Renormalization Group (TRG) methods originally developed for imaginary time. We show that it is effective and efficient in evolving Gaussian wave packets for one and two particles in the disordered phase.
  arXiv  Detail & Related papers  (2024-11-08T03:05:26Z)
• Thermalization and Criticality on an Analog-Digital Quantum Simulator [133.58336306417294]
  We present a quantum simulator comprising 69 superconducting qubits which supports both universal quantum gates and high-fidelity analog evolution. We observe signatures of the classical Kosterlitz-Thouless phase transition, as well as strong deviations from Kibble-Zurek scaling predictions. We digitally prepare the system in pairwise-entangled dimer states and image the transport of energy and vorticity during thermalization.
  arXiv  Detail & Related papers  (2024-05-27T17:40:39Z)
• Nuclear Spectra from Quantum Lanczos Algorithm with Real-Time Evolution and Multiple Reference States [0.0]
  I performed numerical simulations to find the low-lying eigenstates of $20$Ne, $22$Na, and $29$Na to compare imaginary- and real-time evolution. I present the quantum circuits for the QLanczos algorithm with real-time evolution and multiple references.
  arXiv  Detail & Related papers  (2023-09-01T23:25:57Z)
• Quantum Thermal State Preparation [39.91303506884272]
  We introduce simple continuous-time quantum Gibbs samplers for simulating quantum master equations. We construct the first provably accurate and efficient algorithm for preparing certain purified Gibbs states. Our algorithms' costs have a provable dependence on temperature, accuracy, and the mixing time.
  arXiv  Detail & Related papers  (2023-03-31T17:29:56Z)
• Implementation of a two-stroke quantum heat engine with a collisional model [50.591267188664666]
  We put forth a quantum simulation of a stroboscopic two-stroke thermal engine in the IBMQ processor. The system consists of a quantum spin chain connected to two baths at their boundaries, prepared at different temperatures using the variational quantum thermalizer algorithm.
  arXiv  Detail & Related papers  (2022-03-25T16:55:08Z)
• Fast Thermalization from the Eigenstate Thermalization Hypothesis [69.68937033275746]
  Eigenstate Thermalization Hypothesis (ETH) has played a major role in understanding thermodynamic phenomena in closed quantum systems. This paper establishes a rigorous link between ETH and fast thermalization to the global Gibbs state. Our results explain finite-time thermalization in chaotic open quantum systems.
  arXiv  Detail & Related papers  (2021-12-14T18:48:31Z)
• Robust preparation of Wigner-negative states with optimized SNAP-displacement sequences [41.42601188771239]
  We create non-classical states of light in three-dimensional microwave cavities. These states are useful for quantum computation. We show that this way of creating non-classical states is robust to fluctuations of the system parameters.
  arXiv  Detail & Related papers  (2021-11-15T18:20:38Z)
• Computing molecular excited states on a D-Wave quantum annealer [52.5289706853773]
  We demonstrate the use of a D-Wave quantum annealer for the calculation of excited electronic states of molecular systems. These simulations play an important role in a number of areas, such as photovoltaics, semiconductor technology and nanoscience.
  arXiv  Detail & Related papers  (2021-07-01T01:02:17Z)
• Preparation of excited states for nuclear dynamics on a quantum computer [117.44028458220427]
  We study two different methods to prepare excited states on a quantum computer. We benchmark these techniques on emulated and real quantum devices. These findings show that quantum techniques designed to achieve good scaling on fault tolerant devices might also provide practical benefits on devices with limited connectivity and gate fidelity.
  arXiv  Detail & Related papers  (2020-09-28T17:21:25Z)

This list is automatically generated from the titles and abstracts of the papers in this site.

This site does not guarantee the quality of this site (including all information) and is not responsible for any consequences.