Direct quantum process characterization via erasure-based closed timelike curves
- 1Nanjing University
- 2Hefei National Laboratory
Abstract
Characterizing complex quantum evolutions in the microscopic world is crucial for understanding fundamental physics and advancing quantum information applications. In conventional quantum process tomography, individual process matrix elements are obtained indirectly through reconstruction. Here, we use sequential system-ancilla couplings and quantum erasure to directly access these elements for arbitrary quantum processes. Within the pseudo-density-matrix framework, these operations realize an effective erasure-based closed timelike curve (E-CTC) interaction. During E-CTC-assisted measurements, the protocol combines selective computational-basis addressing with fixed superposition preparation and projections. Although the configuration count is not reduced for general processes, these fixed settings can simplify control when computational-basis states are readily addressable. We experimentally demonstrate our scheme in a photonic platform by characterizing several two- and four-dimensional quantum processes with average fidelities above 99 % . Our work offers a basis-rotation-free approach to high-dimensional quantum process characterization within the erasure-based CTC framework.
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BibTeX
@article{yang2026direct,
title = {{Direct quantum process characterization via erasure-based closed timelike curves}},
author = {Ran Yang and Gang Yang and Wei Zhou and Dong-Jie Guo and Xinhui Li and Ji-Ning Zhang and Yu Cui and Yan-Xiao Gong and Shi-Ning Zhu},
journal = {Physical Review Research},
year = {2026},
month = oct,
doi = {10.1103/bskn-3gy3},
url = {https://link.aps.org/doi/10.1103/bskn-3gy3},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Direct quantum process characterization via erasure-based closed timelike curves
AU - Ran Yang
AU - Gang Yang
AU - Wei Zhou
AU - Dong-Jie Guo
AU - Xinhui Li
AU - Ji-Ning Zhang
AU - Yu Cui
AU - Yan-Xiao Gong
AU - Shi-Ning Zhu
PY - 2026
DA - 2026/10/19
JO - Physical Review Research
DO - 10.1103/bskn-3gy3
UR - https://link.aps.org/doi/10.1103/bskn-3gy3
AB - Characterizing complex quantum evolutions in the microscopic world is crucial for understanding fundamental physics and advancing quantum information applications. In conventional quantum process tomography, individual process matrix elements are obtained indirectly through reconstruction. Here, we use sequential system-ancilla couplings and quantum erasure to directly access these elements for arbitrary quantum processes. Within the pseudo-density-matrix framework, these operations realize an effective erasure-based closed timelike curve (E-CTC) interaction. During E-CTC-assisted measurements, the protocol combines selective computational-basis addressing with fixed superposition preparation and projections. Although the configuration count is not reduced for general processes, these fixed settings can simplify control when computational-basis states are readily addressable. We experimentally demonstrate our scheme in a photonic platform by characterizing several two- and four-dimensional quantum processes with average fidelities above 99 % . Our work offers a basis-rotation-free approach to high-dimensional quantum process characterization within the erasure-based CTC framework.
SN - 2643-1564
ER -