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Home → Faculty → Dr. Ching-Yi Lai Associate Professor
Dr. Ching-Yi Lai
Dr. Ching-Yi Lai
Associate Professor
Group:
Wireless Communications
Office:
ED926
Phone:
03-5712121#54545
E-mail:
cylai@nycu.edu.tw
Website:
https://sites.google.com/view/ching-yi-lai
Research:
Error-Control Coding, Information Theory, Fault-Tolerant Quantum Computing
  • Biography
     

    Ching-Yi Lai was born in Taipei, Taiwan. He received his MS in 2006 and BS in 2004 in electrical engineering from National Tsing Hua University, Hsinchu, Taiwan. He received his PhD in 2013 in electrical engineering from the University of Southern California. Since then, he has worked at the Centre for Quantum Software and Information at the University of Technology Sydney and the Institute of Information Science at Academia Sinica in Taiwan. He joined the faculty of the Institute of Communications Engineering at the National Yang Ming Chiao Tung University, Hsinchu, Taiwan in 2018. He was promoted to Associate Professor in 2022.

    Prof. Lai received the MOST Young Scholar Fellowship (哥倫布計畫) in 2018 from the Ministry of Science and Technology, and the Excellent Young Research Fellowship (優秀年輕學者) in 2021. His research interests include coding theory, information theory, quantum computation, and quantum cryptography.

     

    Personal Information:

    o NYCU Academic Hub: https://scholar.nycu.edu.tw/zh/persons/ching-yi-lai


  • Experience, Honors and Awards
    o Association for Algorithms and Computation Best 2023 Journal Paper Award
    o 2023 IEEE Information Society Taipei Chapter and IEEE Communications Society Taipei/Tainan Chapter Best Paper Award for Young Scholars
    o 2021 Ministry of Science and Technology Outstanding Young Scholar Program
    o 2018 Ministry of Science and Technology Young Scholar (Columbus Project)
    o 2017 Postdoctoral Research Scholar at the Academia Sinica (/National Academy of Taiwan) 

    Professional Experience
    o Associate Professor, National Yang Ming Chiao Tung University, Institute of Communications Engineering  (2022.08 ~ present)
    o Assistant Professor, National Yang Ming Chiao Tung University, Institute of Communications Engineering (2018.08 ~ 2022.07)
    o Postdoctoral Researcher,Institute of Information Science, Academia SInica (2015.09 ~ 2018.07)
    o Postdoctoral Researcher,Quantum Software and Information Center, University of Technology Sydney (2013.12 ~ 2015.07)

  • Research Highlights
     

    Belief propagation is the most practical decoding algorithm in traditional communication. However, it cannot effectively handle quantum error correction codes with quantum degeneracy phenomena. It cannot fully play a decoding role in the most valued quantum surface codes currently, and this has been a hard challenge for close to 20 years.

    The complexity of the currently most successful perfect matching algorithms is still relatively high, and it is proportional to the square of the code length. We have provided an answer to solve this challenging problem in this paper. Quantum computing model that is speculated currently is estimated to require around one million quantum bits, and it also requires error correction continuously and rapidly. Therefore, our belief propagation algorithm has a mostly linear complexity, which is advantageous compared to the perfect matching algorithm.

    Moreover, belief propagation algorithms are already mature technologies in traditional communication practices, our algorithm can be combined with the existing chi development in Taiwan and result in a hardware-optimized quantum decoder.


  • Journals
    • Pei-Hao Liou and Ching-Yi Lai,  ``Reducing Quantum Error Correction Overhead with Versatile Flag-Sharing Syndrome Extraction Circuits," 2025.  arXiv:2407.00607
    • Kao-Yueh Kuo and Ching-Yi Lai,  ``Generalized quantum data-syndrome codes and belief propagation decoding for phenomenological noise," IEEE Trans. Inf. Theory, 2025.  arXiv:2310.12682
    • Ching-Yi Lai, Kao-Yueh Kuo, and Bo-Jyun Liao, ``Syndrome decoding by quantum approximate optimization,"  Quant. Inf. Proc., 23, 368, 2024. DOI:10.1007/s11128-024-04568-7 arXiv:2207.05942
    • Ching-Yi Lai, Pin-Chieh Tseng, and Wei-Hsuan Yu, ``Semidefinite programming bounds on the size of entanglement-assisted codeword stabilized quantum codes," IEEE Trans. Inf. Theory, vol. 70, no. 11, pp. 7867-7881, Nov. 2024. DOI:10.1109/TIT.2024.3433550  arXiv:2311.07111
    • Ching-Yi Lai and Kao-Yueh Kuo, ``Harnessing Coding Theory for Reliable Network Quantum Communication," IEEE Wireless Communications, vol. 31, no. 4, pp. 82-88, August 2024. DOI:10.1109/MWC.002.2300308 arXiv:2402.19383 
    • Alexander Barg, Alexey Glazyrin, Wei-Jiun Kao, Ching-Yi Lai, Pin-Chieh Tseng, Wei-Hsuan Yu, ``On the size of maximal binary codes with 2, 3, and 4 distances," Combinatorial Theory, 4(1), 2024. DOI:10.5070/C64163844 arXiv:2210.07496
    • Nai-Hui Chia, Ching-Yi Lai, and Han-Hsuan Lin, ``Efficient learning of t-doped stabilizer states with single-copy measurements," Quantum 8, 1250 (2024). arXiv:2308.07014
    • Pin-Chieh Tseng, Ching-Yi Lai, and Wei-Hsuan Yu, ``Semidefinite programming bounds for binary codes from a split Terwilliger algebra," Des. Codes Cryptogr, 91, 3241–3262, 2023.  DOI: 10.1007/s10623-023-01250-4 
    • Pei-Hao Liou and Ching-Yi Lai, ``Parallel syndrome extraction with shared flag qubits for Calderbank-Shor-Steane codes of distance three," Phys. Rev. A 107, 022614, February 2023.
    • N.-H. Chia, K.-M. Chung and C.-Y. Lai, ``On the Need of Large Quantum Depth," Journal of the ACM, vol. 70, no. 1, article No. 6, pp 1–38, Feb 2023. DOI: 10.1038/s41534-022-00623-2 arXiv:2104.13659  DOI: 10.1145/3570637
    • K.-Y. Kuo and C.-Y. Lai, ``Exploiting Degeneracy in Belief Propagation Decoding of Quantum Codes," npj Quantum Information, 8, Article number: 111, 2022. DOI: 10.1038/s41534-022-00623-2 arXiv:2104.13659 
    • Y. Ouyang, and C.-Y. Lai, ``Linear programming bounds for quantum channels acting on quantum error-correcting codes," IEEE Trans. Inf. Theory, 2022. DOI: 10.1109/TIT.2022.3162264 arXiv:2108.04434
    • C.-Y. Lai, and H.-C. Cheng, ``Learning quantum circuits of some T gates," IEEE Trans. Inf. Theory, 2022. DOI: 10.1109/TIT.2022.3151760 arXiv:2106.12524
    • C.-Y. Lai* and K.-Y. Kuo, ``Log-domain decoding of quantum LDPC codes over binary finite fields," IEEE Trans. Quantum Eng., 2021. DOI: 10.1109/TQE.2021.3113936 arXiv:2104.00304
    • N. Yu, C.-Y. Lai, and L. Zhou, ``Protocols for Packet Quantum Network Intercommunication," IEEE Trans. Quantum Eng., 2021. DOI: 10.1109/TQE.2021.3112594 arXiv:1903.10685
    • K.-Y. Kuo and C.-Y. Lai, ``Refined Belief Propagation Decoding of Sparse-Graph Quantum Codes," IEEE J. Sel. Areas in Inf. Theory, vol. 1, no. 2, pp. 487 - 498, Aug. 2020. DOI: 10.1109/JSAIT.2020.3011758 arXiv:2002.06502
    • L.-Y. Hsu, C.-Y. Lai, Y.-C. Chang, C.-M. Wu and R.-K. Lee, "Carrying an arbitrarily large amount of information using a single quantum particle," Phys. Rev. A 102, 022620, August, 2020.DOI: 10.1103/PhysRevA.102.022620 arXiv:2002.10374
    • Y.-C. Zheng, C.-Y. Lai, T. A. Brun, and L.-C. Kwek, "Constant depth fault-tolerant Clifford circuits for multi-qubit large block codes," Quant. Sci. Tech., 5, 045007, July, 2020. DOI: 10.1088/2058-9565/aba34d arXiv:2003.12328
    • A. Ashikhmin, C.-Y. Lai, and T. A. Brun, "Quantum Data-Syndrome Codes,” IEEE J. Sel. Areas Commun., vol. 38, no. 3, pp. 449 - 462, March 2020. DOI: 10.1109/JSAC.2020.2968997 arXiv:1907.01393
    • K.-M. Chung, M. Georgiou, C.-Y. Lai, and V. Zikas, "Cryptography with Dispensable Backdoors", Cryptography 2019, 3(3), 22, Special issue on Quantum Cryptography and Cyber Security. DOI: 10.3390/cryptography3030022 ePrint Archive: Report 2018/352
    • C.-Y. Lai and K.-M. Chung, "Quantum Encryption and Generalized Quantum Shannon Impossibility," Designs, Codes and Cryptography, 87(9), 1961-1972, 2019. DOI: 10.1007/s10623-018-00597-3 arXiv:1801.03656
    • C.-Y. Lai and K.-M. Chung, "On Statistically-Secure Quantum Homomorphic Encryption," Quant. Inf. Comput., vol. 18, no. 9&10, pp. 0785-0794, 2018. DOI: 10.26421/QIC18.9-10 arXiv:1705.00139
    • Y.-C. Zheng,C.-Y. Lai, and T. A. Brun, "Efficient Preparation of Large Block Code Ancilla States for Fault-tolerant Quantum Computation," Phys. Rev. A, 97, 032331, 2018.  DOI: 10.1103/PhysRevA.97.032331 arXiv:1710.00389
    • Y. Chen, K.-M. Chung, and C.-Y. Lai, "Space-efficient classical and quantum algorithms for the shortest vector problem," Quant. Inf. Comput., vol. 18, no. 3&4, pp. 0283-0305, March 2018.  DOI: 10.26421/QIC18.3-4 arXiv:1709.00378
    • C.-Y. Lai and A. Ashikhmin,"Linear Programming Bounds for Entanglement-Assisted Quantum Error-Correcting Codes by Split Weight Enumerators," IEEE Trans. Inf. Theory, vol. 64, no. 1, pp. 622-639, Jan. 2018. DOI: 10.1109/TIT.2017.2711601 arXiv:1602.00413
    • C.-Y. Lai and R. Duan, "On the One-Shot Zero-Error Classical Capacity of Classical-Quantum Channels Assisted by Quantum Non-signalling Correlations,” Quant. Inf. Comput., vol.17, no. 5&6, pp. 0380-0398, May 2017. DOI: 10.26421/QIC15.5-6 arXiv:1504.06046
    • C.-Y. Lai, Y.-C. Zheng, and T. A. Brun, "Fault-tolerant Preparation of Stabilizer States for Quantum CSS Codes by Classical Error-Correcting Codes,” Phys. Rev. A, 95, 032339, Mar 2017. DOI: 10.1103/PhysRevA.95.032339 arXiv:1605.05647
    • C.-Y. Lai, M.-H. Hsieh, and H.-f. Lu, "On the MacWilliams Identity for Classical and Quantum Convolutional Codes,'' IEEE Trans. Commun., vol. 64, no. 8, pp. 3148-3159, Aug 2016. DOI: 10.1109/TCOMM.2016.2585641 arXiv:1404.5012
    • C.-Y. Lai, G. Paz, M. Suchara, and T. A. Brun, "Performance and Error Analysis of Knill's Postselection Scheme in a Two-Dimensional Architecture," Quant. Inf. Comput., vol.14, no. 9&10, pp. 807-822, July 2014. DOI: 10.26421/QIC14.9-10 arXiv:1305.5657
    • C.-Y. Lai, T. A. Brun, and M. M. Wilde, "Dualities and Identities for Entanglement-Assisted Quantum Codes,'' Quant. Inf. Proc., Vol. 13, no. 4, pp. 957-990, April 2014. DOI: 10.1007/s11128-013-0704-8 arXiv:1010.5506
    • C.-Y. Lai, T. A. Brun, and M. M. Wilde, "Duality in Entanglement-Assisted Quantum Error Correction,'' IEEE Trans. Inf. Theory, vol. 59, no. 6, pp. 4020-4024, June 2013. DOI: 10.1109/TIT.2013.2246274
    • C.-Y. Lai and T. A. Brun, "Entanglement Increases the Error-Correcting Ability of Quantum Error-Correcting Codes,'' Phys. Rev. A, 88, 012320, July 2013. DOI: 10.1103/PhysRevA.88.012320
    • C.-Y. Lai and T. A. Brun, "Entanglement-assisted quantum error-correcting codes with imperfect ebits,'' Phys. Rev. A, 86, 032319, September, 2012. DOI: 10.1103/PhysRevA.86.032319 
    • C.-Y. Lai and C.-C. Lu, "A Construction of Quantum Stabilizer Codes Based on Syndrome Assignment by Classical Parity-Check Matrices,"   IEEE Trans. Inf. Theory, vol. 57, no.10, pp. 7163 - 7179, October 2011. DOI: 10.1109/TIT.2011.2165812

  • Conference Papers
    • Ching-Yi Lai, Pin-Chieh Tseng, and Wei-Hsuan Yu, ``Upper bounds on the size of entanglement-assisted codeword stabilized codes using semidefinite programming,"  2024 IEEE International Symposium on Information Theory (ISIT), Athens, Greece, 2024, pp. 2269-2274, doi: 10.1109/ISIT57864.2024.10619303.
    • Kao-Yueh Kuo and Ching-Yi Lai, ``Decoding Strategies for Generalized Quantum Data-Syndrome Coding Problems," 2024 IEEE International Symposium on Information Theory (ISIT),Athens, Greece, 2024, pp. 2490-2495, doi: 10.1109/ISIT57864.2024.10619431.
    • Ching-Feng Kung, Kao-Yueh Kuo, and Ching-Yi Lai, ``On Belief Propagation Decoding of Quantum Codes with Quaternary Reliability Statistics," 2023 12th International Symposium on Topics in Coding (ISTC), Brest, France, 2023, pp. 1-5, doi: 10.1109/ISTC57237.2023.10273527. arXiv:2305.03321
    • C.-Y. Lai and H.-C. Cheng, ``Learning quantum circuits of T-depth one," 2022 IEEE International Symposium on Information Theory (ISIT), 2022, pp. 2213-2218, DOI: 10.1109/ISIT50566.2022.9834452
    • P.-C. Tseng,C.-Y. Lai, and Wei-Hsuan Yu, ``Improved Semidefinite Programming Bounds for Binary Codes by Split Distance Enumerations," 2022 IEEE International Symposium on Information Theory (ISIT), 2022, pp. 3073-3078, DOI: 10.1109/ISIT50566.2022.9834515
    • K.-Y. Kuo and C.-Y. Lai, ``Comparison of 2D topological codes and their decoding performances," 2022 IEEE International Symposium on Information Theory (ISIT), 2022, pp. 1552-1557. DOI: 10.1109/ISIT50566.2022.9834489 arXiv:2202.06612
    • K.-Y. Kuo, I-Chun Chern, and C.-Y. Lai, ``Decoding of Quantum Data-Syndrome Codes via Belief Propagation," 2021 IEEE International Symposium on Information Theory (ISIT), 2021, pp. 1552-1557. DOI: 10.1109/ISIT45174.2021.9518018 arXiv:2102.01984
    • K.-Y. Kuo and C.-Y. Lai,, ``Refined Belief-Propagation Decoding of Quantum Codes with Scalar Messages," 2020 IEEE Globecom Workshops (GC Wkshps), pp. 1-6), DOI: 10.1109/GCWkshps50303.2020.9367482 arXiv:2102.07122
    • Y. Ouyang, and C.-Y. Lai,"Linear programming bounds for quantum amplitude damping codes," Proc. of IEEE Int. Symp. Inf. Theory (ISIT 2020), Los Angeles, CA, USA, 2020, pp. 1875-1879. DOI: 10.1109/ISIT44484.2020.9174280 arXiv:2001.03976 
    • N.-H. Chia, K.-M. Chung, and C.-Y. Lai, "On the Need of Large Quantum Depth,” Proceedings of the 52nd Annual ACM SIGACT Symposium on Theory of Computing (STOC 2020) , pp.902-915; also accepted as an oral presentation at QIP2020  DOI: 10.1145/3357713.3384291 arXiv:1909.10303
    • D. Aharonov, Z. Brakerski, K.-M. Chung, A. Green, C.-Y. Lai, and O. Sattath, "On Quantum Advantage in Information Theoretic Single-Server PIR," Proc. of Advances in Cryptology – EuroCrypt 2019, pp 219-246, 2019. DOI: 10.1007/978-3-030-17659-4_8 arXiv:1902.09768 ePrint Archive: Report 2019/232
    • K.-Y. Kuo and C.-Y. Lai, "The Encoding and Decoding Complexities of Entanglement-Assisted Quantum Stabilizer Codes," Proc. of IEEE Int. Symp. Inf. Theory (ISIT 2019), pp. 2893-2897, July 2019 in Paris, France. DOI: 10.1109/ISIT.2019.8849380 arXiv:1903.10013
    • C.-Y. Lai and K.-M. Chung, "Interactive Leakage Chain Rule for Quantum Min-entropy,” Proc. of IEEE Int. Symp. Inf. Theory (ISIT 2019), pp. 2997-3001, July 2019, in Paris, France. DOI: 10.1109/ISIT.2019.8849408  arXiv:1809.10694 
    • C.-Y. Lai and A. Ashikhmin, "Linear Programming Bounds for Entanglement-Assisted Quantum Codes," Proc. of IEEE Int. Symp. Inf. Theory (ISIT 2017), pp. 3200-3204, June 2017, in Aachen, Germany. DOI:10.1109/ISIT.2017.8007120
    • A. Ashikhmin, C.-Y. Lai, and T. A. Brun, "Correction of Data and Syndrome Errors by Stabilizer Codes,” Proc. of IEEE Int. Symp. Inf. Theory (ISIT 2016), pp. 2274 - 2278, July 2016, in Barcelona, Spain. DOI: 10.1109/ISIT.2017.8007120
    • C.-Y. Lai, M.-H. Hsieh, and H.-f. Lu, "A Complete MacWilliams Theorem for Convolutional Codes,'' Proc. of IEEE Inf. Theory Workshop (ITW 2014), pp. 157-161, November 2014, in Hobart, Tasmania, Australia. DOI: 10.1109/ITW.2014.6970812
    • C.-Y. Lai and M.-H. Hsieh, "The MacWilliams Identity for Quantum Convolutional Codes,'' Proc. of IEEE Int. Symp. Inf. Theory (ISIT 2014), pp. 911-915, June 2014 in Honolulu. DOI: 10.1109/ISIT.2014.6874965
    • A. Ashikhmin, C.-Y. Lai, and T. A. Brun, "Robust quantum error syndrome extraction by classical coding,” Proc. of IEEE Int. Symp. Inf. Theory (ISIT 2014), pp. 546-550, June 2014, in Honolulu. DOI: 10.1109/ISIT.2014.6874892 
    • M. Suchara, J. Kubiatowicz, A. Faruque, F. Chong, C.-Y. Lai, G. Paz, "QuRE: The Quantum Resource Estimator Toolbox," Proceedings of IEEE International Conference on Computer Design (ICCD 2013), pp. 419-426, October 2013 in Seoul. DOI: 10.1109/ICCD.2013.6657074 (A longer version can be found at arXiv: 1312.2316.)  

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