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S. Saito

Publications and source records attributed to S. Saito.

49 records · Page 3Linked to original sources
arXiv2001

DC-SQUID Sensitivity for Readout of Entangled State Quantum Bits

We propose a scheme for entangled state measurement at flux qubits (quantum bits) depending on the sensitivity measurement of a DC-SQUID (Superconducting QUantum Interference Device). The DC-SQUID is used as a flux qubit readout device. The switching current distribution of a DC-SQUID is sufficiently narrow to distinguish between two ground states of three Josephson junction qubits with a large mutual inductance between a qubit and the DC-SQUID. But discrimination between two ground states becomes difficult with the smaller mutual inductance that is preferable as regards of qubit coherence. However, we can employ averaging to increase the effective sensitivity. And we found that Bell-pair measurement can be performed with flux qubits to prove the existence of an entangled state over two qubits.

cond-mat.supr-con↗
arXiv2001

Atomic Carbon and CO Isotope Emission in the Vicinity of DR15

We present observations of the 3P1-3P0 fine structure transition of atomic carbon [CI], the J=3-2 transition of CO, as well as of the J=1-0 transitions of 13CO and C18O toward DR15, an HII region associated with two mid-infrared dark clouds (IRDCs). The 13CO and C18O J=1-0 emissions closely follow the dark patches seen in optical wavelength, showing two self-gravitating molecular cores with masses of 2000 Msun and 900 Msun, respectively, at the positions of the catalogued IRDCs. Our data show a rough spatial correlation between [CI] and 13CO J=1-0. Bright [CI] emission occurs in relatively cold gas behind the molecular cores, neither in highly excited gas traced by CO J=3-2 emission nor in HII region/molecular cloud interface. These results are inconsistent with those predicted by standard photodissociation region (PDR) models, suggesting an origin for interstellar atomic carbon unrelated to photodissociation processes.

astro-ph↗
arXiv2000

On the behaviour of solutions to discrete time Lotka-Volterra equation

The time evolution of a class of completely integrable discrete Lotka-Volterra s ystem is shown not unique but have two different ways chosen randomly at every s tep of generation. This uncertainty is consistent with the existence of constant s of motion and disappears in both continuous time and ultra discrete limits.

nlin.SI↗
arXiv2000

Quantum Phase Transition in Extended Attractive Hubbard Model

We have made a variational analysis on an evolution of superconductivity from weak to strong coupling regime. In contrast to a crossover without thermodynamic anomaly found in a dilute system, we show the existence of a quantum phase transition near half filling. The transition is driven by charge density waves instabilities. We have found that superconductivity and charge density waves coexist in the presence of a weak intersite repulsion. The ground state phase diagram is determined and the quantum phase transition is an attractive version of the Mott transition.

cond-mat.supr-con↗
arXiv1999

One-loop calculations of hyperon polarizabilities under the large N_c consistency condition

The spin-averaged electromagnetic polarizabilities of the hyperons $Λ$ and $Σ$ are calculated within the one-loop approximation by use of the dispersion theory. The photon and meson couplings to hyperons are determined so as to satisfy the large N_c consistency condition. It is shown that in order for the large N_c consistency condition to hold exotic hyperon states such as $Σ^{**}$ with I=2 and J=3/2 are required in the calculation of the magnetic polarizability of the $Σ$ state.

nucl-th↗
arXiv1999

A new approach to axial coupling constants in the QCD sum rule

We derive new QCD sum rules for the axial coupling constants by considering two-point correlation functions of the axial-vector currents in a one nucleon state. The QCD sum rules tell us that the axial coupling constants are expressed by nucleon matrix elements of quark and gluon operators which are related to the sigma terms and the moments of parton distribution functions. The results for the iso-vector axial coupling constants and the 8th component of the SU(3) octet are in good agreement with experiment.

hep-ph↗
arXiv1999

Spin-Polarizabilities of the Nucleon in Chiral Soliton Model with Dispersion Relation

We calculate the spin-polarizabilities of the nucleon by means of dispersion relation, where the pion photoproduction amplitude predicted by chiral soliton model is utilized. We consider the $Nπ$ and $Δπ$ channels in the pion-photoproduction amplitude, and also evaluate the contribution of the anomalous term of the $π^0γγ$ process. In a narrow decay-width limit of the $Δ$ particle the result coincides with that in heavy baryon chiral perturbation theory (HBChPT) except for the interference part of the electric and magnetic amplitudes. A comparison with the multipole analysis is given.

nucl-th↗
arXiv1998

Finite-dimensional analogs of string s <-> t duality and pentagon equation

We put forward one of the forms of functional pentagon equation (FPE), known from the theory of integrable models, as an algebraic explanation to the phenomenon known in physics as s<->t duality. We present two simple geometrical examples of FPE solutions, one of them yielding in a particular case the well-known Veneziano expression for 4-particle amplitude. Finally, we interpret our solutions of FPE in terms of relations in Lie groups.

solv-int↗
arXiv1998

Laboratory Measurement of the Pure Rotational Transitions of the HCNH+ and its Isotopic Species

The pure rotational transitions of the protonated hydrogen cyanide ion, HCNH+, and its isotopic species, HCND+ and DCND+, were measured in the 107 - 482 GHz region with a source modulated microwave spectrometer. The ions were generated in the cell with a magnetically confined dc-glow discharge of HCN and/or DCN. The rotational constant B0 and the centrifugal distortion constant D0 for each ion were precisely determined by a least-squares fitting to the observed spectral lines. The observed rotational transition frequencies by laboratory spectroscopy and the predicted ones are accurate in about 30 to 40 kHz and are useful as rest frequencies for astronomical searches of HCNH+ and HCND+.

astro-ph↗
arXiv1997

Spin-dependent Polarizability of Nucleon with Dispersion Relation in the Skyrme Model

We calculate the spin-dependent polarizability of the nucleon in the Skyrme model. The result is compared with that of a heavy baryon chiral perturbation theory(HBChPT), and is shown to be the same as that of HBChPT up to the $Δ$-pole terms in the narrow width limit of the $Δ$ state and with the experimental physical constants. The effect of the $Δ+π$ channel is rather small and is numerically quite similar to that of the $Δ$ loop in the HBChPT. The electric and magnetic polarizabilities are recalculated using the transverse photon and a consistent inclusion of the $Δ$ width.

hep-ph↗
arXiv1997

Electric Polarizabilities of Neutral Baryons in the QCD Sum Rule

We investigate the electric polarizabilities of neutral baryons using the method of QCD sum rules. The diagrams in the operator product expansion are taken into account up to dimension 6. We obtain different values of the polarizabilities among hyperons, the ordering of which is given $\barα_n>\barα_{Ξ^0}>\barα_Λ$. The polarizability of ${Σ^0}$, $\barα_{Σ^0}$, has possibly a very small value.

hep-ph↗