Intermediate-temperature topological Uhlmann phase on IBM quantum computers

Fuente: arXiv
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Autori principali: Mastandrea, Christopher, Iancu, Costin, Guo, Hao, Chien, Chih-Chun
Natura: Preprint
Pubblicazione: 2025
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author Mastandrea, Christopher
Iancu, Costin
Guo, Hao
Chien, Chih-Chun
author_facet Mastandrea, Christopher
Iancu, Costin
Guo, Hao
Chien, Chih-Chun
contents A spin-1 system can exhibit an intermediate-temperature topological regime with a quantized Uhlmann phase sandwiched by topologically trivial low- and high-temperature regimes. We present a quantum circuit consisting of system and ancilla qubits plus a probe qubit which prepares an initial state corresponding to the purified state of a spin-1 system at finite temperature, evolves the system according to the Uhlmann process, and measures the Uhlmann phase via expectation values of the probe qubit. Although classical simulations suggest the quantized Uhlmann phase is observable on IBM's noisy intermediate-scale quantum (NISQ) computers, an implementation of the circuit without any optimization exceeds the gate count for the error budget and results in unresolved signals. Through a series of optimization with Qiskit and BQSQit, the gate count can be substantially reduced, making the jumps of the Uhlmann phase more visible. A recent hardware upgrade of IBM quantum computers further improves the signals and leads to a clearer demonstration of interesting finite-temperature topological phenomena on NISQ hardware.
format Preprint
id arxiv_https___arxiv_org_abs_2508_02915
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Intermediate-temperature topological Uhlmann phase on IBM quantum computers
Mastandrea, Christopher
Iancu, Costin
Guo, Hao
Chien, Chih-Chun
Quantum Physics
Other Condensed Matter
A spin-1 system can exhibit an intermediate-temperature topological regime with a quantized Uhlmann phase sandwiched by topologically trivial low- and high-temperature regimes. We present a quantum circuit consisting of system and ancilla qubits plus a probe qubit which prepares an initial state corresponding to the purified state of a spin-1 system at finite temperature, evolves the system according to the Uhlmann process, and measures the Uhlmann phase via expectation values of the probe qubit. Although classical simulations suggest the quantized Uhlmann phase is observable on IBM's noisy intermediate-scale quantum (NISQ) computers, an implementation of the circuit without any optimization exceeds the gate count for the error budget and results in unresolved signals. Through a series of optimization with Qiskit and BQSQit, the gate count can be substantially reduced, making the jumps of the Uhlmann phase more visible. A recent hardware upgrade of IBM quantum computers further improves the signals and leads to a clearer demonstration of interesting finite-temperature topological phenomena on NISQ hardware.
title Intermediate-temperature topological Uhlmann phase on IBM quantum computers
topic Quantum Physics
Other Condensed Matter
url https://arxiv.org/abs/2508.02915