An official website of the United States government
The spectra of two-dimensional su(2) gauge theories coupled to a single massless Majorana fermion in integer representations, J, are numerically investigated using the discrete light-cone Hamiltonian. One of our aims is to explore the possible presence of massless states for J > 2 in spite of the absence of a continuous symmetry. After comparing to existing results for J = 1 (adjoint fermions), we present results for J = 2, 3, 4. As expected, for J = 2 there are no massless states but in contrast to the J = 1 theory, the lightest state is a boson. We find exact massless modes in the bosonic and fermionic sector for all values of total momentum for J = 3 and J = 4 and, in each sector, the number of massless modes grows with the value of the total momentum. In addition to the spectrum, we present results on the particle number and momentum fraction distributions and argue for a separation of bulk states from edge states.
more »
« less
Observation of dynamical fermionization
The wave function of a Tonks-Girardeau (T-G) gas of strongly interacting bosons in one dimension maps onto the absolute value of the wave function of a noninteracting Fermi gas. Although this fermionization makes many aspects of the two gases identical, their equilibrium momentum distributions are quite different. We observed dynamical fermionization, where the momentum distribution of a T-G gas evolves from bosonic to fermionic after its axial confinement is removed. The asymptotic momentum distribution after expansion in one dimension is the distribution of rapidities, which are the conserved quantities associated with many-body integrable systems. Our measurements agree well with T-G gas theory. We also studied momentum evolution after the trap depth is suddenly changed to a new nonzero value, and we observed the theoretically predicted bosonic-fermionic oscillations.
more »
« less
- PAR ID:
- 10180353
- Date Published:
- Journal Name:
- Science
- Volume:
- 367
- Issue:
- 6485
- ISSN:
- 0036-8075
- Page Range / eLocation ID:
- 1461 to 1464
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
[This paper is part of the Focused Collection in Investigating and Improving Quantum Education through Research.] We discuss how research on student difficulties was used as a guide to develop, validate, and evaluate a Quantum Interactive Learning Tutorial (QuILT) to help students learn how to determine the completely symmetric bosonic or completely antisymmetric fermionic wave function and be able to compare and contrast them from the case when the particles can be treated as distinguishable. We discuss how explicit scaffolding is designed via guided teaching-learning sequences for two- or three-particle bosonic and fermionic systems to help students develop intuition about how to construct completely symmetric and antisymmetric wave function, both when spin part of the wave function is ignored and when both spatial and spin degrees of freedom are included. Published by the American Physical Society2025more » « less
-
null (Ed.)By harnessing quantum phenomena, quantum devices have the potential to outperform their classical counterparts. Here, we examine using wave function symmetry as a resource to enhance the performance of a quantum Otto engine. Previous work has shown that a bosonic working medium can yield better performance than a fermionic medium. We expand upon this work by incorporating a singular interaction that allows the effective symmetry to be tuned between the bosonic and fermionic limits. In this framework, the particles can be treated as anyons subject to Haldane’s generalized exclusion statistics. Solving the dynamics analytically using the framework of “statistical anyons”, we explore the interplay between interparticle interactions and wave function symmetry on engine performance.more » « less
-
null (Ed.)A bstract We study two-dimensional celestial conformal field theory describing four- dimensional $$ \mathcal{N} $$ N =1 supergravity/Yang-Mills systems and show that the underlying symmetry is a supersymmetric generalization of BMS symmetry. We construct fermionic conformal primary wave functions and show how they are related via supersymmetry to their bosonic partners. We use soft and collinear theorems of supersymmetric Einstein-Yang- Mills theory to derive the OPEs of the operators associated to massless particles. The bosonic and fermionic soft theorems are shown to form a sequence under supersymmetric Ward identities. In analogy with the energy momentum tensor, the supercurrents are shadow transforms of soft gravitino operators and generate an infinite-dimensional super- symmetry algebra. The algebra of $$ {\mathfrak{sbms}}_4 $$ sbms 4 generators agrees with the expectations based on earlier work on the asymptotic symmetry group of supergravity. We also show that the supertranslation operator can be written as a product of holomorphic and anti-holomorphic supercurrents.more » « less
-
null (Ed.)The recently proposed map [5] between the hydrodynamic equationsgoverning the two-dimensional triangular cold-bosonic breathers [1] andthe high-density zero-temperature triangular free-fermionic clouds, bothtrapped harmonically, perfectly explains the former phenomenon butleaves uninterpreted the nature of the initial(t=0)singularity. This singularity is a density discontinuity that leads, inthe bosonic case, to an infinite force at the cloud edge. The map itselfbecomes invalid at times t<0 t < 0 .A similar singularity appears at t = T/4 t = T / 4 ,where Tis the period of the harmonic trap, with the Fermi-Bose map becominginvalid at t > T/4 t > T / 4 . Here, we first map—using the scale invariance of the problem—thetrapped motion to an untrapped one. Then we show that in the newrepresentation, the solution [5] becomes, along a ray in the directionnormal to one of the three edges of the initial cloud, a freelypropagating one-dimensional shock wave of a class proposed by Damski in[7]. There, for a broad class of initial conditions, the one-dimensionalhydrodynamic equations can be mapped to the inviscid Burgers’ equation,which is equivalent to a nonlinear transport equation. Morespecifically, under the Damski map, thet=0singularity of the original problem becomes, verbatim, the initialcondition for the wave catastrophe solution found by Chandrasekhar in1943 [9]. At t=T/8 t = T / 8 ,our interpretation ceases to exist: at this instance, all threeeffectively one-dimensional shock waves emanating from each of the threesides of the initial triangle collide at the origin, and the 2D-1Dcorrespondence between the solution of [5] and the Damski-Chandrasekharshock wave becomes invalid.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript
- Journal Article:
- https://doi.org/10.1126/science.aaz0242
