Quantum Process Tomography with Digital Twins of Error Matrices
Accurate and robust quantum process tomography (QPT) is crucial for verifying quantum gates and diagnosing implementation faults in experiments aimed at building universal quantum computers. However, the reliability of QPT protocols is often compromised by faulty probes, particularly state preparation and measurement (SPAM) errors, which introduce fundamental inconsistencies in traditional QPT algorithms. We propose and investigate enhanced QPT for multiqubit systems by integrating the error matrix in a digital twin of the identity process matrix, enabling statistical refinement of SPAM error learning and improving QPT precision. Through numerical simulations, we demonstrate that our approach enables highly accurate and faithful process characterization. We further validate our method experimentally in superconducting quantum processors, achieving at least an order-of-magnitude fidelity improvement over standard QPT. Our results provide a practical and precise method for assessing quantum gate fidelity and enhancing QPT on a given hardware.
Authors
- Akshay Gaikwad (ORCID: https://orcid.org/0009-0001-2243-6185)
- Ilya N. Moskalenko (ORCID: https://orcid.org/0000-0002-4864-824X)
- Mamta Dahiya (ORCID: https://orcid.org/0000-0001-6824-769X)
- Jonas Bylander (ORCID: https://orcid.org/0000-0003-4521-710X)
- G. S. Paraoanu (ORCID: https://orcid.org/0000-0003-0057-7275)
- Andreas Nylander (ORCID: https://orcid.org/0000-0002-9724-1892)
- Irshad Ahmad (ORCID: https://orcid.org/0000-0003-2607-0093)
- Tangyou Huang (ORCID: https://orcid.org/0000-0003-2824-769X)
- Ognjen Stanisavljević
- Janka Biznárová (ORCID: https://orcid.org/0000-0002-8887-8816)
- Giovanna Tancredi (ORCID: https://orcid.org/0000-0002-3628-8398)
- Anton Frisk Kockum (ORCID: https://orcid.org/0000-0002-2534-3021)
- Tahereh Abad (ORCID: https://orcid.org/0000-0002-6277-3477)
- Amr Osman (ORCID: https://orcid.org/0000-0002-0290-1000)
- Marko Kuzmanović (ORCID: https://orcid.org/0000-0002-1773-1702)
- Christopher Warren (ORCID: https://orcid.org/0000-0001-6195-2708)
- Yu‐Han Chang (ORCID: https://orcid.org/0009-0009-8536-3954)
- Marcus Rommel (ORCID: https://orcid.org/0000-0002-3026-3907)
- Liangyu Chen (ORCID: https://orcid.org/0000-0002-5072-2445)
- Anuj Aggarwal (ORCID: https://orcid.org/0009-0008-0323-3658)
- Emil Hogedal
- Anita Fadavi Rousari
Institutions
- Chalmers University of Technology (SE)
- Aalto University (FI)
Publication Details
- Journal
- Physical Review Letters
- Published
- 2025-11-13
- DOI
- https://doi.org/10.1103/dpgy-rtxr
- Primary Topic
- Quantum Computing Algorithms and Architecture
- Type
- article
- Field-Weighted Citation Impact
- 0.00
Funders
- Stiftelsen för Strategisk Forskning
- Aalto-Yliopisto
- Wallenberg Center for Quantum Technology, Chalmers University of Technology