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Quantum Information Science

High-performance computing (HPC) and secure communication (SC) are the foundations of comfortable and secure network environments. The next generation of high-speed networks will require more advanced HPC and SC technologies. Quantum computing and quantum cryptography are regarded as the ultimate innovative technological solutions. We are studying quantum information science, including quantum computing and quantum cryptography, with the aim of finding new algorithms and protocols.

Research Topics

Automatic Quantum Circuit Design

We gave a classical algorithm that generates efficient quantum circuits by using a certain kind of matrix decomposition technique.

  • Nakajima. Y., Kawano, Y., Sekigawa, H., Nakanishi, M., Yamashita, S. and Nakashima, Y., Synthesis of Quantum Circuits for d-level Systems by using Cosine-Sine Decomposition, Quantum Information and Computation, Vol.9 No.5&6, pp.423-443, 2009. [Online Journal]

Efficient Quantum Circuit for Addition

We developed a fast quantum circuit for addition with few qubits by using the ripple-carry and carry-lookahead methods.

  • Takahashi, Y. and Kunihiro, N., A fast quantum circuit for addition with few qubits, Quantum Information and Computation, Vol. 8 No. 6&7, pp. 636-649, 2008.[Online Journal]

Recent Publications

2012

  • Cleve, R., Iwama, K., Le Gall, F., Nishimura, H., Tani, S., Teruyama, J., and Yamashita, S.: Reconstructing strings from substrings with quantum queries. Proc. of Scandinavian Symposium and Workshops on Algorithm Theory, to appear (2012).
  • Kubota, T., Kakutani, T., Kato G., Kawano, Y., and Sakurada, H.: Application of a Process Calculus to Security Proofs of Quantum Protocols, The 2012 International Conference on Foundations of Computer Science, in press (2012).
  • Tani, S. and Kobayashi, H., and Matsumoto, K.: Exact quantum algorithms for the leader election problem. ACM Transactions on Computation Theory, Vol.4, No.1 (2012).
  • Tani, S.: Compression of View on Anonymous Networks -- Folded View --. IEEE Transactions on Parallel and Distributed Systems, Vol.23, No.2, pp.255-262 (2012).

2011

  • Owari, M. and Hayashi, M.: Asymptotic local hypothesis testing between a pure bipartite state and the completely mixed state. The 15th Workshop on Quantum Information Processing (QIP 2012) (2011).
  • Kawano, Y.: Extended Clifford Group Circuit and Applications. The 15th Workshop on Quantum Information Processing (QIP 2012) (2011).
  • Aaronson, S., Le Gall, F., Russell, A., and Tani, S.: The one-way communication complexity of group membership. Chicago Journal of Theoretical Computer Science, No. 6 (2011).
  • Takahashi, Y.: An approximately universal set consisting of two observables. International Journal of Quantum Information, Vol.9, No.6, pp.1393-1412 (2011).
  • Kawano, Y.: Extended Clifford Group Circuit and Application, Asian Quantum Information Science Conference 2011 (AQIS 2011) (2011).
  • Kawano, Y., and Sekigawa, H.: Algorithm for QFT Circuits on Symmetric Groups, Asian Quantum Information Science Conference 2011 (AQIS 2011) (2011).
  • Takahashi, Y.: An approximately universal set consisting of two observables. The 6th Conference on Theory of Quantum Computation, Communication, and Cryptography (TQC 2011) (2011).
  • Kubota, T., Kakutani, T., Kato G., and Kawano, Y.: A Formal Approach to Unconditional Security Proofs for Quantum Key Distribution. The 10th International Conference on Unconventional Computation (UC 2011), Springer Lecture Notes in Computer Science Vol.6714, pp.125-137 (2011).
  • Takahashi, Y.: Simple sets of measurements for universal quantum computation and graph state preparation. Proc. of the 5th Conference on Theory of Quantum Computation, Communication, and Cryptography (TQC 2010), Lecture Notes in Computer Science, Springer, Vol.6519, pp.26-34 (2011).
  • Kawano, K.: Hidden shift problem for quadratic functions on a product of cyclic groups. The 14th Workshop on Quantum Information Processing (QIP 2011) (2011).
  • Kawano, Y. and Sekigawa, H.: Matrix decomposition and its application to complex Hadamard matrices. The 14th Workshop on Quantum Information Processing (QIP 2011) (2011).
  • Takahashi, Y.: Reducing the resources of measurement-only quantum computation. The 14th Workshop on Quantum Information Processing (QIP 2011) (2011).
  • Kato, G. and Tamaki, K.: Security of six-state quantum key distribution protocol with threshold detectors. The 14th Workshop on Quantum Information Processing (QIP 2011) (2011).

2010

  • Kato, G.: Optimal cloning of qubits from replicas of a qubit and its orthogonal states. Phys. Rev. A 82, 032314(2010).
  • Tamaki, K. and Kato, G.: Quantum circuit for security proof without encryption of error syndrome and noisy processing. Phys. Rev. A 81, 022316 (2010).
  • Takahashi, Y., Tani, S. and Kunihiro, N.: Quantum addition circuits and unbounded fan-out. Quantum Information and Computation, Vol.10, No.9&10, pp.872-890 (2010).
  • Takahashi, Y.: Simple sets of measurements for universal quantum computation and graph state preparation. International Journal of Quantum Information, Vol.8, No.6, pp.1001-1012 (2010).
  • Kato, G.: Optimal cloning of qubits from replicas of a qubit and the states orthogonal to it. Updating Quantum Cryptography and Communications 2010 (UQCC 2010) (2010).
  • Tamaki, K. and Kato, G.: Quantum circuit for security proof of quantum key distribution without encryption of error syndrome and noisy processing. Updating Quantum Cryptography and Communications 2010 (UQCC 2010) (2010).
  • Kubota, T., Kakutani, T., Kato G., Kawano, Y.: Formal Approach for Security Proof of a QKD Protocol. Updating Quantum Cryptography and Communications 2010 (UQCC 2010) (2010).
  • Tamaki, K. and Kato, G.: Quantum circuit for security proof of quantum key distribution without encryption of error syndrome and noisy processing. 10th Asian Conference on Quantum Information Science (AQIS 2010) (2010).
  • Kubota, T., Kakutani, T., Kato G., Kawano, Y.: Towards Automation of Unconditional Security Proof of QKD. 10th Asian Conference on Quantum Information Science (AQIS 2010) (2010).
  • Kato, G.: Optimal cloning of qubits from replicas of a qubit and its orthogonal states. The 13th Workshop on Quantum Information Processing (QIP 2010) (2010).
  • Kawano, Y. and Sekigawa, H.: Application of Matrix Decomposition to Finding Complex Hadamard Matrices. The 13th Workshop on Quantum Information Processing (QIP 2010) (2010).
  • Takahashi, Y., Tani, S. and Kunihiro, N.: Quantum addition circuits and unbounded fan-out. The 13th Workshop on Quantum Information Processing (QIP 2010) (2010).
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