1,263 research outputs found
Predominant Magnetic States in Hubbard Model on Anisotropic Triangular Lattices
Using an optimization variational Monte Carlo method, we study the
half-filled-band Hubbard model on anisotropic triangular lattices, as a
continuation of the preceding study [J. Phys. Soc. Jpn 75, 074707 (2006)]. We
introduce two new trial states: (i) A coexisting state of
(\pi,\pi)-antiferromagnetic (AF) and a d-wave singlet gaps, in which we allow
for a band renormalization effect, and (ii) a state with an AF order of
120^\circ spin structure. In both states, a first-order metal-to-insulator
transition occurs at smaller U/t than that of the pure d-wave state. In
insulating regimes, magnetic orders always exist; an ordinary (\pi,\pi)-AF
order survives up to t'/t\sim 0.9 (U/t=12), and a 120^\circ-AF order becomes
dominant for t'/t \gsim 0.9. The regimes of the robust superconductor and of
the nonmagnetic insulator the preceding study proposed give way to these
magnetic domains.Comment: 11 pages, 14 figure
Demonstration of a Controlled-Phase Gate for Continuous-Variable One-Way Quantum Computation
We experimentally demonstrate a controlled-phase gate for continuous
variables in a fully measurement-based fashion. In our scheme, the two
independent input states of the gate, encoded in two optical modes, are
teleported into a four-mode Gaussian cluster state. As a result, one of the
entanglement links present in the initial cluster state appears in the two
unmeasured output modes as the corresponding entangling gate acting on the
input states. The genuine quantum character of this gate becomes manifest and
is verified through the presence of entanglement at the output for a product
two-mode coherent input state. By combining our controlled-phase gate with the
recently reported module for universal single-mode Gaussian operations [R. Ukai
et al., Phys. Rev. Lett. 106, 240504 (2011)], it is possible to implement
universal Gaussian operations on arbitrary multi-mode quantum optical states in
form of a fully measurement-based one-way quantum computation.Comment: 4 pages, 3 figure
Variational Monte Carlo studies of a t-J model on an anisotropic triangular lattice
With the insulating phase of \kappa-(BEDT-TTF)_2X in mind, we study a t-J
model on an anisotropic triangular lattice, where the hopping integral is t' in
one of the three directions, using a variational Monte Carlo method. By
changing the value of t'/t, we study the stability of superconducting (SC)
states with d- and d+id-wave symmetries and of an antiferromagnetic (AF) state.
As t'/t decreases from 1, the stable state immediately switches from the d+id
wave to the d wave. The AF state is stabilized from the normal spin liquid
state for t'/t\lsim 0.7 at half filling. We also take account of Nagaoka
ferromagnetism and a phase separation.Comment: 4 pages, 3 figure
On the Terrestrial Earthworm Fauna of Yamagata Prefecture, northeastern Japan
We conducted to collect earthworms in order to clarify the earthworm fauna of Yamagata Prefecture. We could collect 16 species belonging to two families including two undescribed species from six localities. To our knowledge, it is first time to record Pheretima aokii, P. megascolidioides, P. micronaria and Aporrectodea caliginosa from Yamagata Prefecture. Therefore, except for two species which could not identified as known species, 18 valid species of earthworms exist in Yamagata Prefecture including our result. Keywords : earthworm fauna, Megascolecidae, Lumbricidae, Oligochaeta, Yamagata Prefectur
Generation of one-million-mode continuous-variable cluster state by unlimited time-domain multiplexing
In recent quantum optical continuous-variable experiments, the number of
fully inseparable light modes has drastically increased by introducing a
multiplexing scheme either in the time domain or in the frequency domain. Here,
modifying the time-domain multiplexing experiment reported in Nature Photonics
7, 982 (2013), we demonstrate successive generation of fully inseparable light
modes for more than one million modes. The resulting multi-mode state is useful
as a dual-rail CV cluster state. We circumvent the previous problem of optical
phase drifts, which has limited the number of fully inseparable light modes to
around ten thousands, by continuous feedback control of the optical system.Comment: 12 pages, 8 figure
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