Program
Thursday, August 15
Location 375 LeConte Hall
10:30 am - Coffee
11:00 am - Welcome
11:10 am - 11:45 am
Invited Talk: Neil Glikin (UC Berkeley)
Coherent control of rotating ion strings: towards observing quantum statistics in a new regime
The symmetrization of identical quantum particles has been elegantly demonstrated in many ways, including by the creation of degenerate quantum gases, by direct spectroscopy of systems of molecules, and by Hong-Ou-Mandel-type interference. I will describe experiments towards the goal of a well-controlled few-particle demonstration of the symmetrization of Âcalcium-40 ions by way of direct, coherent particle exchange. Such an exchange can be performed by preparing a coherent superposition of rotating many-body states and waiting for an appropriate exchange time. We utilize a unique circularly symmetric surface-electrode Paul trap to create a two-dimensional rotor potential, which admits angular momentum eigenstates, and demonstrate coherent control of the states of two ions in this rotor. We aim to use this control to perform direct particle exchange, allowing us to study the emergence of indistinguishability even for particles which are always separated by many micrometers.
11:45 am - 12:20 pm
Invited Talk: Adam Bowman (Stanford)
Wide-field electro-optic imaging and applications to microscopy
We demonstrate new electro-optic techniques for wide-field imaging of fast dynamics and fluorescence lifetimes. Our approach removes conventional limits on throughput, efficiency, and speed in time-correlated single particle counting and gated camera systems. We show fast fluorescence lifetime imaging microscopy with 3-5 orders of magnitude higher throughput than single photon counting, lifetime spectroscopy of single molecules, and application to single particle tracking. Finally, we combine re-imaging optics with temporal gating to allow multi-frame nanosecond imaging. By enabling image modulation, multiplexing, and gating from nanosecond to millisecond timescales, these techniques may find broad applications ranging from fluorescence microscopy and clinical diagnostics to lock-in detection and time-of-flight imaging.
12:20 - 2 pm: Lunch
Berkeley students will lead the way to various locations near campus.
2:00 - 2:35 pm
Invited Talk: Stephen Taylor (Stanford)
Imaging Nematic Transitions in Iron-Pnictide Superconductors with a Quantum Gas
The SQCRAMscope is a recently realized Scanning Quantum CRyogenic Atom Microscope that utilizes an atomic Bose-Einstein condensate to measure magnetic fields emanating from solid-state samples. The quantum sensor does so with unprecedented DC sensitivity at micron resolution from room-to-cryogenic temperatures. An additional advantage of the SQCRAMscope is the preservation of optical access to the sample: Magnetometry imaging of, e.g., electron transport may be performed in concert with other imaging techniques. This multimodal imaging capability can be brought to bear with great effect in the study of nematicity in iron-pnictide high-temperature superconductors, where the relationship between electronic and structural symmetry-breaking resulting in a nematic phase is under debate. Here, we combine the SQCRAMscope with an in situ microscope that measures optical birefringence near the surface. This enables simultaneous and spatially resolved detection of both bulk and surface manifestations of nematicity via transport and structural deformation channels, respectively. By performing the first local measurement of emergent resistivity anisotropy in iron pnictides, we observe a spatially inhomogeneous increase in the temperature at which optical birefringence appears near the surface over that at which anisotropic local transport appears within the bulk. This is consistent with the existence of a higher-temperature so-called `extraordinary' surface nematic transition, albeit one that emerges inhomogeneously. More broadly, these measurements demonstrate the SQCRAMscope's ability to reveal important insights into the physics of complex quantum materials.
2:35 - 3:10 pm
Invited Talk: Vicky Xu (Berkeley)
Probing gravity by holding atoms for 20 seconds
Atom interferometers are powerful tools for both measurements in fundamental physics and inertial sensing applications. Their performance, however, has been limited by the available interrogation time of freely falling atoms in a gravitational field. We realize an unprecedented interrogation time of 20 seconds by suspending the spatially-separated atomic wavepackets in a lattice formed by the mode of an optical cavity. Unlike traditional atom interferometers, this approach allows potentials to be measured by holding, rather than dropping, atoms. After seconds of hold time, gravitational potential energy differences from as little as microns of vertical separation generate megaradians of interferometer phase. This trapped geometry suppresses the phase sensitivity to vibrations by 3-4 orders of magnitude, overcoming the dominant noise source in atom-interferometric gravimeters. Finally, we study the wavefunction dynamics driven by gravitational potential gradients across neighboring lattice sites.
3:10 - 3:30 pm: Snack Break
3:40 - 6:00 pm: Lab Tours
6:00 pm: Dinner (self-organized)