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- Takayuki Miyadera, Masanori Ohya
- Open Syst. Inform. Dynam.
- 2005

We prove that there is no algorithm to tell whether an arbitrarily constructed Quantum Turing Machine has same time steps for different branches of computation. We, hence, can not avoid the notion of halting to be probabilistic in Quantum Turing Machine. Our result suggests that halting scheme of Quantum Turing Machine and quantum complexity theory based… (More)

We derive a novel version of information-disturbance theorems for mutually unbiased observables. We show that the information gain by Eve inevitably makes the outcomes by Bob in the conjugate basis not only erroneous but random.

- Alexandru Gheorghiu, Elham Kashefi, +12 authors PetrosWallden andElhamKashefi
- 2017

The relationship between correlations and entanglement has played amajor role in understanding quantum theory since thework of Einstein et al (1935Phys. Rev. 47 777–80). Tsirelson proved that Bell states, shared among twoparties, whenmeasured suitably, achieve themaximumnon-local correlations allowed by quantummechanics (Cirel’son 1980 Lett.Math. Phys. 4… (More)

- Akira Shimizu, Takayuki Miyadera
- Physical review letters
- 2002

We study the stability of quantum states of macroscopic systems of finite volume V. By using both the locality and huge degrees of freedom, we show the following: (i) If square fluctuation of every additive operator is O(V) or less for a pure state, then it is not fragile for any weak classical noises or weak perturbations from environments. (ii) If square… (More)

- Atushi Tanaka, Hiroshi Fujisaki, Takayuki Miyadera
- Physical review. E, Statistical, nonlinear, and…
- 2002

The production of quantum entanglement between weakly coupled mapping systems, whose classical counterparts are both strongly chaotic, is investigated. In the weak-coupling regime, it is shown that time-correlation functions of the unperturbed systems determine the entanglement production. In particular, we elucidate that the increment of the nonlinear… (More)

- Masakazu Yoshida, Takayuki Miyadera, Hideki Imai
- 2010 International Symposium On Information…
- 2010

It is anticipated that quantum key distribution enable us to share a secret key while guaranteeing unconditionally security. In this paper, we discuss the quantum key distribution using the Mean King Problem which was proposed by J. Bub in 2001. While this two-way quantum protocol is essentially different from the other one-way protocols like the BB84, it… (More)

- Hiroshi Fujisaki, Takayuki Miyadera, Atushi Tanaka
- Physical review. E, Statistical, nonlinear, and…
- 2003

We investigate how the dynamical production of quantum entanglement for weakly coupled, composite quantum systems is influenced by the chaotic dynamics of the corresponding classical system, using coupled kicked tops. The linear entropy for the subsystem (a kicked top) is employed as a measure of entanglement. A perturbative formula for the entanglement… (More)

- Takayuki Miyadera
- Entropy
- 2011

In this paper, a representation of the information-disturbance theorem based on the quantum Kolmogorov complexity that was defined by P. Vitányi has been examined. In the quantum information theory, the information-disturbance relationship, which treats the trade-off relationship between information gain and its caused disturbance, is a fundamental result… (More)

A limitation on simultaneous measurement of two arbitrary positive operator valued measures is discussed. In general, simultaneous measurement of two noncommutative observables is only approximately possible. Following Werner’s formulation, we introduce a distance between observables to quantify an accuracy of measurement. We derive an inequality that… (More)

It has been shown that Information-Disturbance theorem can play an important role in security proof of quantum cryptography. The theorem is by itself interesting since it can be regarded as an information theoretic version of uncertainty principle. It, however, has been able to treat restricted situations. In this paper, the restriction on the source is… (More)