Broken axisymmetry phase of a spin-1 ferromagnetic Bose-Einstein condensate

A spin-1 ferromagnetic Bose-Einstein condensate subject to a certain magnetic field exhibits a broken-axisymmetry phase in which the magnetization tilts against the applied magnetic field due to the competition between ferromagnetism and linear and quadratic Zeeman effects. The Bogoliubov analysis shows that in this phase two Goldstone modes associated with U(1) and SO(2) symmetry breakings exist, in which phonons and magnons are coupled to restore the two broken symmetries.Comment: 11 pages, 6 figure

QCD resummation in hard diffractive dijet production at the electron-ion collider

Diffractive dijet production at the electron-ion collider (EIC) has been proposed to study the gluon Wigner distribution at small-x. We investigate the soft gluon radiation associated with the final state jets and an all order resummation formula is derived. We show that the soft gluon resummation plays an important role to describe E791 data on π-induced diffractive dijet production at Fermilab. Predictions for the EIC are presented, and we emphasize that the soft gluon resummation is an important aspect to explore the nucleon/nucleus tomography through these processes

Bogoliubov Theory and Lee-Huang-Yang Corrections in Spin-1 and Spin-2 Bose-Einstein Condensates in the Presence of the Quadratic Zeeman Effect

We develop Bogoliubov theory of spin-1 and spin-2 Bose-Einstein condensates (BECs) in the presence of a quadratic Zeeman effect, and derive the Lee-Huang-Yang (LHY) corrections to the ground-state energy, sound velocity, and quantum depletion. We investigate all the phases of spin-1 and spin-2 BECs that can be realized experimentally. We also examine the stability of each phase against quantum fluctuations and the quadratic Zeeman effect. Furthermore, we discuss a relationship between the number of symmetry generators that are spontaneously broken and that of Nambu-Goldstone (NG) modes. It is found that in the spin-2 nematic phase there are special Bogoliubov modes that have gapless linear dispersion relations but do not belong to the NG modes.Comment: v3: 62 pages, 18 figure

The second law of thermodynamics under unitary evolution and external operations

The von Neumann entropy cannot represent the thermodynamic entropy of equilibrium pure states in isolated quantum systems. The diagonal entropy, which is the Shannon entropy in the energy eigenbasis at each instant of time, is a natural generalization of the von Neumann entropy and applicable to equilibrium pure states. We show that the diagonal entropy is consistent with the second law of thermodynamics upon arbitrary external unitary operations. In terms of the diagonal entropy, thermodynamic irreversibility follows from the facts that quantum trajectories under unitary evolution are restricted by the Hamiltonian dynamics and that the external operation is performed without reference to the microscopic state of the system.Fruitful discussions with Masahiro Hotta, Takashi Mori, Takahiro Sagawa, and Takanori Sugiyama are gratefully acknowledged. This work was supported by KAKENHI 26287088, a Grant-in-Aid for Scientific Research on Innovation Areas "Topological Quantum Phenomena" (KAKENHI 22103005), and the Photon Frontier Network Program, from MEXT of Japan. T.N.I. acknowledges the JSPS for financial support (Grant No. 248408). N.S. was supported by a Grant-in-Aid for JSPS Fellows (Grant No. 250588). (26287088 - KAKENHI; 22103005 - KAKENHI; Photon Frontier Network Program, from MEXT of Japan; 24840 - JSPS; 250588)Accepted manuscrip

"Currency intervention and the global portfolio balance effect: Japanese and Swiss lessons, 2003-2004 and 2009-2010"

This paper shows that the Japanese and Swiss foreign exchange interventions in 2003/04 and 2009/10 seem to have lowered long-term interest rates in a range of industrial countries, including Japan and Switzerland. It seems that this decline was triggered by the investment of the intervention funds in US and euro area bonds and that a global portfolio balance effect made this decline in interest rate spread to other markets, thus easing monetary conditions at home and abroad.