Broadband spin-wave quantum memories in cold and ultracold atomic systems
Abstract: Quantum memories using cold and ultracold atoms are a promising platform for storing and manipulating photonic signals, and will be a key component in quantum communications systems, especially in realizing critical quantum repeater infrastructure. Cold atoms have significant potential as high performance spin-wave quantum memories, due to the long storage times associated with low temperature and slow thermal diffusion. Broadband, low-noise performance in such memories is also required, but these two principles are often at odds with each other.
Replica symmetry breaking in a cavity QED spin glass
Abstract: Spin glasses are canonical examples of complex matter. Although much about their structure remains uncertain, they inform the description of a wide array of complex phenomena, ranging from magnetic ordering in metals with impurities to aspects of evolution, protein folding, climate models, and artificial intelligence, where spin glass theory forms a mathematical basis for neuromorphic computing.
Quantum in the Army and Rydberg Receivers
Abstract: Why does the Army care about quantum mechanics? In this JQI Seminar, Dr. Kevin Cox will discuss what it's like to be a physicist at the Army Research Laboratory and talk about how his group is using Rydberg atoms to create radio-frequency receivers that can sense the entire spectrum.
*You will need to bring your cell phone, so you can sign in. For Zoom, please submit a chat saying hello with your first and last name, so you can receive lunch. Lunch will be served after the seminar only to the individuals that have attended.*
Qubit-Oscillator Concatenated Codes: Decoding Formalism and Code Comparison
Concatenating bosonic error-correcting codes with qubit codes can substantially boost the error-correcting power of the original qubit codes. It is not clear how to concatenate optimally, given that there are several bosonic codes and concatenation schemes to choose from, including the recently discovered Gottesman-Kitaev-Preskill (GKP) – stabilizer codes [Phys. Rev. Lett. 125, 080503 (2020)] that allow protection of a logical bosonic mode from fluctuations of the conjugate variables of the mode.
Analysis of SoS Relaxations for the Quantum Rotor Model
The noncommutative sum-of-squares (ncSoS) hierarchy was introduced by Navascues--Pironio--Acin as a sequence of semidefinite programming relaxations for approximating values of "noncommutative polynomial optimization problems," which were originally intended to generalize quantum values of nonlocal games. Recent work has started to analyze the hierarchy for approximating ground energies of local Hamiltonians, initially through rounding algorithms which output product states for degree-2 ncSoS.
Full counting statistics as a probe of chaotic and integrable dynamics
Abstract: Experiments with ultracold gases and digital quantum simulators can take simultaneous snapshots of all the particles in a system. Unlike conventional response experiments, these snapshots encode arbitrarily high-order correlation functions. It is natural to ask what new information these high-order correlations contain. I will present solvable models, as well as experimental data, showing how these new probes can elucidate (and disprove) certain proposed mechanisms for many-body dynamics.
Investigating the feasibility of a trapped atom interferometer with movable traps
Atom interferometers can be used to obtain information about accelerations and fields, whether this may be in the investigation of fundamental aspects of physics, such as measuring fundamental constants or testing gravity, or as part of a measurement device, such as an accelerometer [1,2,3]. Achieving adequate coherence times remains a priority, and this can be realized by holding the atoms in a trap as an alternative to increasing their free fall time [1].