Recent progress in Hamiltonian learning
Abstract: In the last few years, a number of works have proposed and improved provably efficient algorithms for learning the Hamiltonian from real-time dynamics. In this talk, I will first provide an overview of these developments, and then discuss how the Heisenberg limit, the fundamental precision limit imposed by quantum mechanics, can be reached for this task. I will show that reaching the Heisenberg limit requires techniques that are fundamentally different from previous ones.
Quantum Advantage Without Speed-Ups
Abstract: Quantum cryptography leverages unique features of quantum mechanics in order to construct cryptographic primitives which are oftentimes impossible for digital computers. Cryptographic applications of quantum computers therefore have the potential for useful quantum advantage – entirely without computational speed-ups. In this talk, I will focus on two fundamental questions: First, is it possible to certify that private data has been deleted? And second, is it possible to revoke a cryptographic key?
Embracing Uncertainty Helps Bring Order to Quantum Chaos
In physics, chaos is something unpredictable. A butterfly flapping its wings somewhere in Guatemala might seem insignificant, but those flits and flutters might be the ultimate cause of a hurricane over the Indian Ocean. The butterfly effect captures what it means for something to behave chaotically: Two very similar starting points—a butterfly that either flaps its wings or doesn’t—could lead to two drastically different results, like a hurricane or calm winds.
But there's also a tamer, more subtle form of chaos in which similar starting points don’t cause drastically different results—at least not right away. This tamer chaos, known as ergodicity, is what allows a coffee cup to slowly cool down to room temperature or a piece of steak to heat up on a frying pan. It forms the basis of the field of statistical mechanics, which describes large collections of particles and how they exchange energy to arrive at a shared temperature. Chaos almost always grows out of ergodicity, forming its most eccentric variant.
Quantum interference of radiations from many atoms and many excited levels
Abstract: At the heart of modern quantum technologies is the interference in the radiation of quantum emitters mediated by common vacuum modes. When there are many atoms interfering in the emission process, one observes enhancement or suppression of decay rate coefficient, which is called superradiance and subradiance, respectively [1]. When there are transitions from different excited levels interfering in the emission process, the intensity of the emitted light is modulated at the frequency of the excited level splittings, which is called quantum beats.
Getting to know QuICS
Abstract: In this session, new and current QuICS members will introduce themselves and their research. Organized by Yi-Kai Liu.
Investigating the feasibility of a trapped atom interferometer with movable traps
Abstract: Atom interferometers can be used for diverse applications, ranging from the exploration of fundamental aspects of physics, such as measuring field parameters or testing gravity [1, 2], to employment as a measurement device, for instance, an accelerometer or in rotation sensing [3,4].
Building a quantum internet with photons and electron spins
Abstract: How do we get quantum systems to ‘talk’ to each other? How can we distribute entanglement at global scales? I will describe our work tackling these challenges by using light as a robust mediator of quantum interactions between matter qubits. First, I overview the development of optically-active electron spins in silicon carbide as a platform to realize long-distance quantum links. These qubits uniquely combine world-record spin coherence, noiseless single photon emission, and nanophotonic device integration- all in a wafer-scale semiconductor.
Advocating for Quantum Simulations of Extreme Physics
The Big Bang, supernovae, collisions of nuclei at breakneck speeds—our universe is filled with extreme phenomena, both natural and human-made. But the surprising thing is that all of these seemingly distinct processes are governed by the same underlying physics: a combination of quantum mechanics and Einstein’s theory of special relativity known as quantum field theory.
Graduate Student’s Initiative Opened the Way to Numerous Research Collaborations and Accolades at UMD
A big part of research is working with other scientists. As an undergraduate and JQI graduate student at the University of Maryland, Jacob Bringewatt has put in the work knocking on doors and connecting with professors, which has allowed him to explore a broad range of research projects and earned him accolades along the way.
Quantum ergodicity beyond random matrices
Abstract: The fundamental assumption of statistical mechanics is that the long-time average of any observable is equal to its average over the microcanonical ensemble. In classical mechanics, this stems from Boltzmann’s ergodic hypothesis, by which a generic initial state in an ergodic system visits the neighborhood of all states in phase space with the same energy. However, wavelike effects in quantum mechanics have made it difficult to identify what it even means for a quantum system to be ergodic, except on a case-by-case basis for individual observables.