Superconductivity wins election over dissipation
In 1962 Josephson predicted that an electric current can flow with no applied voltage through a thin insulating layer separating two superconductors. Since then, such "Josephson junction" has become has become the routinely used in many quantum electronic circuits (squids magnetometers, parametric amplifiers, superconducting qubits,...) and its use in the Volt metrology has helped reshape the International System of Units around quantum effects.
Coherence and decoherence in the Harper-Hofstadter model
Understanding how and when closed quantum systems lose or retain coherence is a central intellectual and practical question in quantum science. In rare cases, such as collisional narrowing or environment assisted tunneling, random processes can enhance coherence processes. In this talk, I will present a new addition to this list—the quasi-periodic lattice described by the Harper-Hofstadter (HH) model in a highly-elongated tube geometry, by showing that the dynamics can be immune to environmental noise.
Ultracold bubbles in space: atomic physics aboard the International Space Station
Exploring the effects of geometry, topology, dimensionality, and interactions on ultracold atomic ensembles has proven to be a continually fruitful line of inquiry. One heretofore unexplored configuration for such ensembles is that of a bubble or shell, where trapped atoms are confined in the vicinity of a spherical or ellipsoidal surface.
Faster Digital Quantum Simulation by Symmetry Protection
Simulating the dynamics of quantum systems is an important application of quantum computers and has seen a variety of implementations on current hardware. We show that by introducing quantum gates implementing unitary transformations generated by the symmetries of the system, one can induce destructive interference between the errors from different steps of the simulation, effectively giving faster quantum simulation by symmetry protection. We derive rigorous bounds on the error of a symmetry-protected simulation algorithm and identify conditions for optimal symmetry protection.
Harnessing biosystems for quantum information science
It is well known that architectures for quantum sensing and quantum information processing require exceptional isolation from sources of decoherence, including electromagnetic and thermal noise, by shielding and cooling. Could robust room-temperature alternatives be envisioned using biosystems that are optimized for certain quantum processes in warm, wet, and wiggly environments?
Dynamics of Confined Domain Walls in a Quantum Simulator
Confinement is a ubiquitous mechanism in nature, whereby particles feel an attractive force that increases without bound as they separate. A prominent example is color confinement in particle physics, in which baryons and mesons are produced by quark confinement. Analogously, confinement can also occur in low-energy quantum many-body systems when elementary excitations are confined into bound quasiparticles. We report the observation of magnetic domain wall confinement in an interacting spin chain with a trapped-ion quantum simulator.
Quantum In The Wild
RSVP: go.umd.edu/dulny
The importance of the spectral gap in estimating ground-state energies
The field of quantum Hamiltonian complexity lies at the intersection of quantum many-body physics and computational complexity theory, with deep implications to both fields. The main object of study is the LocalHamiltonian problem, which is concerned with estimating the ground-state energy of a local Hamiltonian. A major challenge in the field is to understand the complexity of the LocalHamiltonian problem in more physically natural parameter regimes.
The importance of the spectral gap in estimating ground-state energies
The field of quantum Hamiltonian complexity lies at the intersection of quantum many-body physics and computational complexity theory, with deep implications to both fields. The main object of study is the LocalHamiltonian problem, which is concerned with estimating the ground-state energy of a local Hamiltonian. A major challenge in the field is to understand the complexity of the LocalHamiltonian problem in more physically natural parameter regimes.
The multi-terminal Josephson effect
Junctions of more than two superconducting terminals are required for implementing braiding operations on Majorana fermions. Moreover, such multi-terminal Josephson Junctions (JJ) were predicted to support topological state and host zero-energy quasiparticles. Unlike conventional two-terminal JJs where the value of critical current is a number, the multi-terminal JJs exhibit a novel feature – the critical current contour (CCC).