Debbie Leung profile picture

Institute for Quantum Computing (IQC)

Research Associate Faculty

Areas of research: Quantum Information

(519) 888-4567 x33604

http://www.math.uwaterloo.ca/~wcleung/

Research Interests
I study the capacity of communicating various form of data (quantum, private, or classical) through quantum channels, focusing on the superadditivity phenomenon. I also study how quantum entanglement, in particular, embezzlement of entanglement, plays a role in quantum information theory.
Positions Held
  • Tolman Postdoctoral Fellow, Theoretical Physics Institute for Quantum Information, Caltech, 2002-2005
  • Postdoctoral Fellow, Quantum Computation Mathematical Sciences Research Institute, Berkeley, 2002
  • Postdoctoral Fellow, Information group IBM T.J. Watson Research Center, 2000-2002
Awards
  • Alliance International Collaboration UKRI Quantum Grant (ALLRP), Natural Sciences and Engineering Research Council of Canada, 2025
  • NSERC Discovery grant, Natural Sciences and Engineering Research Council of Canada, 2024
  • NSERC QUORUM project, Natural Sciences and Engineering Research Council of Canada, 2023
  • Discovery Grant, Natural Sciences and Engineering Research Council of Canada (NSERC), 2016-2024
Recent Publications
  • Agarwal, A., Kalra, A. R., Lee, S., Leung, D., Schaeffer, L., Sinha, P., & Smith, G. (2026). Enhanced quantum capacity thresholds from symmetry. https://arxiv.org/abs/2605.09138v2
  • Khanian, Z., Lee, D., Leung, D., Li, Z., May, A., Mori, T., . . . Yoshida, B. (2026). Entanglement sharing schemes. doi:10.48550/arxiv.2509.21462
  • Agarwal, A., Bu, A., Kalra, A. R., Leung, D., Schaeffer, L., & Smith, G. (2026). On Error Thresholds for Pauli Channels: Some answers with many more questions. https://arxiv.org/abs/2603.04357v1
  • Hayden, P., Leung, D., Rall, H., & Salek, F. (2026). Efficiently Computable Limits on EPR Pair Generation in Quantum Broadcast Channels. IEEE Transactions on Information Theory, PP(99), 1. doi:10.1109/tit.2026.3695699
  • Asadi, V. R., Kuroiwa, K., Leung, D., May, A., Pasterski, S., & Waddell, C. (2025). Conditional disclosure of secrets with quantum resources. Quantum, 9, 1885. doi:10.22331/q-2025-10-16-1885
  • Hayden, P., Leung, D., Rall, H., & Salek, F. (2025). Efficiently Computable Limits on EPR Pair Generation in Quantum Broadcast Channels. doi:10.48550/arxiv.2505.07218
  • Khanian, Z. B., & Leung, D. (2025). Quantum Reverse Shannon Theorem Revisited. doi:10.48550/arxiv.2504.07068
  • Grier, D., Leung, D., Li, Z., Pashayan, H., & Schaeffer, L. (2025). Streaming quantum state purification for general mixed states. https://arxiv.org/abs/2503.22644v1
  • Liu, A. Z., & Leung, D. (2025). Fault-tolerant Preparation of Distant Logical Bell Pair -- with application in the magic square game. https://arxiv.org/abs/2503.13673v1
  • Khanian, Z. B., Kuroiwa, K., & Leung, D. (2025). Rate-Distortion Theory for Mixed States. IEEE Transactions on Information Theory, 71(2), 1077-1095. doi:10.1109/tit.2024.3509825
  • Childs, A. M., Fu, H., Leung, D., Li, Z., Ozols, M., & Vyas, V. (2025). Streaming quantum state purification. Quantum, 9, 1603. doi:10.22331/q-2025-01-21-1603
  • Khanian, Z. B., Kuroiwa, K., & Leung, D. (2024). Rate-Distortion Theory for Mixed States. doi:10.48550/arxiv.2208.11698
  • Khanian, Z. B., Kuroiwa, K., & Leung, D. (2023). Rate-Distortion Theory for Mixed States. In 2023 IEEE International Symposium on Information Theory (ISIT) Vol. 00 (pp. 749-754). Institute of Electrical and Electronics Engineers (IEEE). doi:10.1109/isit54713.2023.10206960
  • Leditzky, F., Leung, D., Siddhu, V., Smith, G., & Smolin, J. A. (2023). The Platypus of the Quantum Channel Zoo. IEEE Transactions on Information Theory, 69(6), 3825-3849. doi:10.1109/tit.2023.3245985
  • Leditzky, F., Leung, D., Siddhu, V., Smith, G., & Smolin, J. A. (2023). Generic Nonadditivity of Quantum Capacity in Simple Channels. Physical Review Letters, 130(20), 200801. doi:10.1103/physrevlett.130.200801
  • Kuroiwa, K., & Leung, D. (2023). Rate reduction of blind quantum data compression with local approximations based on the unstable structure of quantum states. Physical Review A, 107(5), 052421. doi:10.1103/physreva.107.052421
Seminars
  • Quantum state purification, CIFAR Quantum Information Science Program meeting, Banff Center, Canada., Canadian Institute for Advanced Research, Toronto, Canada, 2026/03/25
  • Quantum state purification, Operator Algebras and Quantum Information Program seminar, Institut Mittag-Leffler, 2026/02/18
  • Open problems in communication over restricted quantum networks, FirstPrinciples Quantum Information Workshop, Cambridge, Toronto, Waterloo, 2026/02/18
  • Generic non-additivity of quantum channel capacities, 2025 IEEE Information Theory Workshop (IEEE-ITW 2025), Sydney, Australia., 2025/10/01
  • Quantum state purification, 25th Asian Quantum Information Science Conference (AQIS2025), University of Hong Kong., 2025/08/04
  • Channel capacities, classical vs quantum, Canadian Undergraduate Mathematical Conference, University of Waterloo, Canada, 2025/06/24
  • Generic non-additivity of quantum channel capacities, 2025 Biennial Symposium on Communications, Sherbrooke, Canada, 2025/06/05
  • Super-additivity of quantum channel capacities, Ontario Graduate Mathematics Conference, Field's Institute, Canada, 2025/05/30
  • Purifying noisy quantum states, Bristol Quantum Information Theory seminar, University of Bristol, 2024/12/04
  • The platypus of the quantum channel zoo and their generic nonadditivity, 2024/10/26
  • Purifying arbitrarily noisy quantum states, Hong Kong University of Science and Technology (Guangzhou), Quantum Information Tech Salon (QITS), 2024/10/10
  • Purifying arbitrarily noisy quantum states, Tutte colloquium, University of Waterloo, Combinatorics and Optimization, 2024/10/04
  • Christopher King Memorial Lecture, Beyond IID in Information Theory 12, University of Illinois Urbana-Champaign, Jul 29 -- Aug 02, 2024., 2024/07/31
  • Quantum Information and Computation, Stanford Program for Inspiring the Next Generation of Women in Physics (SPINWIP), Stanford University, Palo Alto (virtual). July 8-26, 2024., 2024/07/16
  • Additive quantities cannot be more than asymptotically continuous, InQubator for Quantum Simulation seminar, University of Washington, Seattle (virtual)., 2024/05/01
  • The platypus of the quantum channel zoo, Quantum Information and Computing seminar, Texas Tech University, Lubbock (virtual)., 2024/04/17
  • Purifying arbitrarily noisy quantum states, 2024 Center for Quantum Frontiers of Research \& Technology (QFort) Workshop, National Cheng Kung University, Tainan, Taiwan. April 15-17, 2024, 2024/04/17
  • Purifying arbitrarily noisy quantum states, Fundamental Limitations to Quantum Computation, Banff International Research Station, Alberta, Canada. March 4-8, 2024., 2024/03/07
  • Quantum state purification, Quantum Information Workshop, SwissMAP Research Station, Les Diablerets, Switzerland. February 26 - March 02, 2024., 2024/02/26
  • The platypus of the quantum channel zoo and their generic nonadditivity, Southwest Quantum Information and Technology, 25th Annual SQuInT Workshop, University of New Mexico, Albuquerque, New Mexico. October 26-28, 2023, 2023/10/26
  • Rate-Distortion Theory for Mixed States, Analytical and Combinatorial Methods in Quantum Information Theory II, International Centre for Mathematical Sciences, Edinburgh, United Kingdom, 2023/07/28