21 Result(s)
within
S. S. Nazin
Physics
English
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Article
Screening and edge states in two-dimensional metals in a magnetic field
The length λ0 at which the lateral electric-field component E ⊥ perpendicular to the boundary is conserved near the boundary of two-dimensional (2D) samples, which is covered by 2D electro...
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Article
Relativistic constraints on the distinguishability of orthogonal quantum states
The constraints imposed by special relativity on the distinguishability of quantum states are discussed. An explicit expression relating the probability of an error in distinguishing two orthogonal single-phot...
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Relativistic quantum protocols: Bit commitment and coin tossing
New relativistic quantum protocols realizing the bit commitment and coin tossing schemes are proposed. The protocols are based on the idea that spatially extended nonstationary orthogonal quantum states inacce...
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Article
The role of causality in ensuring the ultimate security of relativistic quantum cryptography
One of the central points of quantum information theory is the problem of ultimate security of quantum cryptography; i.e., the security that is due only to the fundamental laws of nature rather than to technic...
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Article
A simple proof of unconditional security of relativistic quantum cryptography
A simple proof of the unconditional security of a relativistic quantum cryptosystem based on orthogonal states is given. Limitations imposed by the special relativity theory allow the proof to be markedly simp...
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Article
Quantum bit commitment in a channel with noise
Under rather general assumptions about the properties of a quantum channel with noise, a quantum protocol providing implementation of secret bit commitment with the probability as close to unity as is wished i...
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Article
Relativistic quantum bit commitment in real-time
A relativistic quantum exchange protocol making it possible to implement a bit commitment scheme is realized. The protocol is based on the idea that in the relativistic case the propagation of a field into a r...
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Relativistic quantum coin tossing
A relativistic quantum exchange protocol enabling “coin tossing at a distance” between two participants is proposed. The exchange protocol is based on the fact that to distinguish a pair of orthogonal states w...
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Article
Teleportation of a continuous variable
Measurements used in quantum teleportation are examined from the standpoint of the general theory of quantum-mechanical measurements. It is shown that in order to find a teleported state, it is sufficient to k...
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Article
The Einstein-Podolsky-Rosen effect and causality
It is shown for a simple example that the formalism of quantum field theory and the requirement of microcausality do not forbid complete correlation of the results of measurements performed by two observers se...
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Measurement of the state of an individual spin using a “turnstile”
A scheme is proposed for measuring the state of an individual spin (system of spins). The scheme is based on the idea of a single-electron “turnstile” and the injection of single spin-polarized electrons from ...
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Article
Soft Edge Magnetoplasmons in 2D Circular Pools of He4 ions
The recent experimental discovery of anomalous soft edge magnetoplasmons (EMP) in 2D charged systems 1,2 and the problem of their identification requires an analys...
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Article
Nonstationary-states quantum cryptography
A quantum cryptosystem is proposed in which a pair of nonstationary states differing in their times of preparation is used as the information carriers.
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Article
Generation of one-photon states by a quantum dot
A technique for preparation of a one-photon wave packet through action of a classical electromagnetic field on a semiconducting quantum dot is proposed. We demonstrate that the Coulomb repulsion between charge...
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Article
Quantum cryptography based on homodyne detection (vacuum-state cryptosystem)
A new protocol is proposed for quantum cryptography. The protocol is based on the use of a set of measurements which make it possible to reconstruct completely the density matrix — the information carrier — of...
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Article
Is there a fundamental limit on the length of a communication channel in a single-photon quantum cryptosystem?
It is shown that there is no formal limit on the length of the communication channel in a single-photon quantum cryptosystem with arbitrary dispersion if there is no dam** in the communication line. A prescr...
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Quantum cryptography based on the energy-time uncertainty relation
A new quantum cryptosystem based on the energy-time uncertainty relation is proposed. This cryptosystem can be implemented with both biphotonic states and single photons.
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Article
Macroscopic quantum tunneling in small magnetic particles
Macroscopic quantum tunneling of magnetization in small antiferromagnetic clusters is studied for the spin-1/2 anisotropic (J z ≡ J, J x =J ...
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Article
Quantum cryptography based on quantum dots
Network protocols are formulated for the phase-coding and correlated-photon-pairs quantum cryptosystems. These protocols are free of the restriction imposed on the distance between the two legitimate users by ...
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Article
Soft edge magnetoplasmons in 2D systems with smooth density profile
Recent experimental discovery of novel soft edge magnetoplasmons (EMP) in a circular pool of He+ ions trapped below the surface of liquid helium [1] identified as the modes occurring due to smooth density profile...
