10 research outputs found
Observation of a metallic superfluid in a numerical experiment
We report the observation, in Monte Carlo simulations, of a novel type of
quantum ordered state: {\it the metallic superfluid}. The metallic superfluid
features ohmic resistance to counter-flows of protons and electrons, while
featuring dissipationless co-flows of electrons and protons. One of the
candidates for a physical realization of this remarkable state of matter is
hydrogen or its isotopes under high compression. This adds another potential
candidate to the presently known quantum dissipationless states, namely
superconductors, superfluid liquids and vapours, and supersolids.Comment: 4 pages, 2 figures. Accepted for publication in Phys. Rev. Let
Violation of the London Law and Onsager-Feynman quantization in multicomponent superconductors
Non-classical response to rotation is a hallmark of quantum ordered states
such as superconductors and superfluids. The rotational responses of all
currently known single-component "super" states of matter (superconductors,
superfluids and supersolids) are largely described by two fundamental
principles and fall into two categories according to whether the systems are
composed of charged or neutral particles: the London law relating the angular
velocity to a subsequently established magnetic field and the Onsager-Feynman
quantization of superfluid velocity. These laws are theoretically shown to be
violated in a two-component superconductor such as the projected liquid
metallic states of hydrogen and deuterium at high pressures. The rotational
responses of liquid metallic hydrogen or deuterium identify them as a new class
of dissipationless states; they also directly point to a particular
experimental route for verification of their existence.Comment: Nature Physics in print. This is an early version of the paper. The
final version will be posted 6 months after its publication Nature Physics,
according to the journal polic
Criticality in the 2+1-dimensional compact Higgs model and fractionalized insulators
We use a novel method of computing the third moment M_3 of the action of the
2+1-dimensional compact Higgs model in the adjoint representation with q=2 to
extract correlation length and specific heat exponents nu and alpha, without
invoking hyperscaling. Finite-size scaling analysis of M_3 yields the ratio
(1+alpha)/nu and 1/nu separately. We find that alpha and nu vary along the
critical line of the theory, which however exhibits a remarkable resilience of
Z_2 criticality. We propose this novel universality class to be that of the
quantum phase transition from a Mott-Hubbard insulator to a
charge-fractionalized insulator in two spatial dimensions.Comment: 4 pages, 3 figures, submitted to Phys. Rev. Let
The phases of deuterium at extreme densities
We consider deuterium compressed to higher than atomic, but lower than
nuclear densities. At such densities deuterium is a superconducting quantum
liquid. Generically, two superconducting phases compete, a "ferromagnetic" and
a "nematic" one. We provide a power counting argument suggesting that the
dominant interactions in the deuteron liquid are perturbative (but screened)
Coulomb interactions. At very high densities the ground state is determined by
very small nuclear interaction effects that probably favor the ferromagnetic
phase. At lower densities the symmetry of the theory is effectively enhanced to
SU(3), and the quantum liquid enters a novel phase, neither ferromagnetic nor
nematic. Our results can serve as a starting point for investigations of the
phase dynamics of deuteron liquids, as well as exploration of the stability and
dynamics of the rich variety of topological objects that may occur in phases of
the deuteron quantum liquid, which range from Alice strings to spin skyrmions
to Z_2 vortices.Comment: 9 pages, 6 figures; v2: fixed typo
Type-1.5 superconductivity in multicomponent systems
In general a superconducting state breaks multiple symmetries and, therefore, is characterized by several different coherence lengths , . Moreover in multiband material even superconducting states that break only a single symmetry are nonetheless described, under certain conditions by multi-component theories with multiple coherence lengths. As a result of that there can appear a state where some coherence lengths are larger and some are smaller than the magnetic field penetration length : . That state was recently termed "type-1.5" superconductivity. This breakdown of type-1/type-2 dichotomy is rather generic near a phase transition between superconducting states with different symmetries. The examples include the transitions between and states or between and states. The later example is realized in systems that feature transition between s-wave and states. The extra fundamental length scales have many physical consequences. In particular in these regimes vortices can attract one another at long range but repel at shorter ranges. Such a system can form vortex clusters in low magnetic fields. The vortex clustering in the type-1.5 regime gives rise to many physical effects, ranging from macroscopic phase separation in domains of different broken symmetries, to unusual transport properties