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Quantum Information Processing

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 processing theory, 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

2011

  • Takahashi, Y.: An approximately universal set consisting of two observables. The 6th Conference on Theory of Quantum Computation, Communication, and Cryptography (TQC 2011), to appear.
  • 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), to appear.
  • Tani, S.: Compression of View on Anonymous Networks -- Folded View ---. IEEE Transactions on Parallel and Distributed Systems, in press.
  • 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).
  • 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).

2009

  • Tani, T.: Claw finding algorithms using quantum walk. Theoretical Computer Science, Vol. 410, No. 50, pp. 5285–5297(2009).
  • Kobayashi, H., Matsumoto, K., and Tani, S.: Exactly electing a unique leader is not harder than computing symmetric functions on anonymous quantum networks. Proc. of the Twenty-Eighth Annual ACM Symposium on Principles of Distributed Computing (PODC 2009), pp. 334–335(2009).
  • Takahashi, Y., Tani, S. and Kunihiro, N.: Quantum addition circuits and unbounded fan-out. Proc. of Asian Conference on Quantum Information Science (AQIS2009), pp.45-46(2009).
  • 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).
  • Kawano, Y., and Sekigawa, H.: Producing Quantum Circuits of the Extended Clifford Group using KAK decomposition, Twelfth Workshop on Quantum Information Processing (QIP 2009)(2009).
  • Kato, G.: Quantum cloning of qubits with orthogonal states as hints, Twelfth Workshop on Quantum Information Processing (QIP 2009)(2009).
  • Ambainis, A., Iwama. K., Nakanishi, M., Nishimura, H., Raymond, R., Tani, S. and Yamashita, S.: Average/Worst-case Gaps of Quantum Query Complexities. Twelfth Workshop on Quantum Information Processing (QIP 2009)(2009).
  • Tani, S., Nakanishi, M. and Yamashita, S.: Multi-party quantum communication complexity with routed messages. IEICE Transactions on Information and Systems, Vol.E92-D, No.2, pp.191–199(2009).
  • Kato, G.: Cloning of qubits with both the cloned state and the state orthogonal to it as inputs, Phys. Rev. A 79, 032315(2009).
  • Takahashi, Y.: Quantum arithmetic circuits: a survey. IEICE Trans. Fundamentals, Vol.E92-A No.5, pp.1276-1283(2009).
  • Takahashi, Y. and Kunihiro, N: Circuit for Shor's factoring algorithm with at most 2n+2 qubits. The 4th Workshop on Theory of Quantum Computation, Communication, and Cryptography(2009).
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