JQI Seminar

Abstract: A quantum impulse is a brief but strong perturbation that produces a sudden change in a wavefunction.

Abstract: It may seem unlikely that rich mathematical structures remain to be uncovered in classical harmonic oscillators. Nevertheless, systems that combine non-reciprocity and loss have provided a number of surprises in recent years. I will describe how these systems naturally exhibit braids, knots, and other topological structures. I will also present measurements of these structures (using a cavity optomechanical system), and will describe their potential application in various control schemes.

Abstract: Quantum information science seeks to exploit the collective behavior of a large quantum system to enable tasks that are impossible (or less possible!) with classical resources alone. This burgeoning field encompasses a variety of directions, ranging from metrology to computing. While distinguished in objective, all of these directions rely on the preparation and control of many identical particles or qubits. Meeting this need is a defining challenge of the field.

Abstract: Precise control of quantum states allows atom interferometers to explore fundamental physics and perform inertial sensing. For atomic fountain interferometers, the measurement time is limited by the available free-fall time to a few seconds. We instead realize atom interferometry with a coherent spatial superposition state held by an optical lattice beyond 1 minute. This performance was made possible by recent advances in the understanding and control of coherence-limiting mechanisms.

Abstract: Quantum sensors will broadly impact industries including transportation and logistics, telecommunications, aerospace, defense, and geophysical exploration. They offer transformative performance gains over conventional technologies; atomic clocks are precise to 1 second in 50 billion years. However, these laboratory devices are large, fragile, and expensive. Commercial quantum devices require redesign from the ground up with a focus on real-world operability.

Abstract: We consider the logical gate of (3+1)D Z2 gauge theory with an emergent fermionic particle, and point out that pumping the p+ip topological state through the 3d space defines the emergent Z8 global symmetry. We then show that in the context of stabilizer quantum codes, one can obtain logical CCZ and CS gates by placing the code on a discretization of T^3 (3-torus) and mapping torus of T^2 respectively, and pumping p+ip states. Our considerations also imply the possibility of a logical T gate by placing the code on RP3 and pumping a p+ip topological state.

Abstract: This talk will consist of two parts. First, we will discuss passively protected quantum memories, in which an encoded qubit is coupled to an environment that naturally corrects errors. For example, we will present a candidate for a passively protected quantum memory in two dimensions. Second, we will discuss how entanglement in a network of quantum sensors can be used to accurately measure properties of spatially varying fields.

Abstract: Polyatomic molecules uniquely enable the simultaneous combination of multiple features advantageous for precision measurement. Searches for charge-parity (CP) violation benefit from large internal molecular fields, high polarizability, internal co-magnetometry, and the ability to cycle photons - all of which can be found in certain polyatomic species. We discuss experimental and theoretical developments in several linear metal hydroxide (MOH) species.

Abstract: Multi-mode continuous-variable entanglement has become increasingly important for practical quantum information processing. We generate 2-mode vacuum-squeezed optical states through a 4-wave mixing (4WM) process in Rb atomic vapor and conduct a detailed study using homodyne measurements. By dividing the squeezing bandwidth into smaller frequency bins, we show that different sideband frequencies represent independent sources of two-mode squeezing.

Abstract: Kerr optical frequency combs are generated by pumping an integrated microresonator with a resonant laser.