Events at Physics |
Events on Monday, November 3rd, 2025
- Plasma Physics (Physics/ECE/NE 922) Seminar
- Title to be announced
- Time: 12:00 pm - 1:00 pm
- Place: 2241 Chamberlin Hall
- Speaker: Felix Parra-Diaz, PPPL
- Host: Cary Forest
- Preliminary Exam
- Direct measurement of the energy spectrum of a quantum dot artificial molecule
- Time: 12:30 pm - 2:00 pm
- Place: Chamberlin Hall Room 5310
- Speaker: Jack Reily
- Abstract: Quantum dot artificial atoms in semiconducting SiGe/Si/SiGe heterostructures, formed by strong electronic confinement, are promising scalable qubit systems. The single- and few-electron spectra consist of multiple valley-orbital levels, which, in general, modify tunnel couplings and qubit dynamics, which is relevant for qubit encoding and readout. Here, we provide a new method of directly measuring the energy spectrum of an artificial molecule for fixed electron number. By tuning square wave pulses along the delta axis of the artificial molecule, we show how the curvature governed by excited-to-excited, ground-to-excited, and ground-to-ground couplings can all be extracted simultaneously. This new measurement provides the ability to extract many relevant Hamiltonian parameters, which are necessary for the precise operation and control of spin qubits.
- Host: Albrecht Karle
- Theory Seminar (High Energy/Cosmology)
- Probing Dark Matter with Pulsar Timing Arrays and Gravitational Wave Detectors
- Time: 1:00 pm - 2:30 pm
- Place: Chamberlin 5280
- Speaker: Vincent S.H. Lee, UC, Berkeley
- Abstract: Pulsar timing arrays (PTAs) and gravitational wave detectors can serve as valuable tools in the detection of dark matter. Dark matter substructure within the Milky Way Galaxy can induce gravitational pulls on pulsars, leading to observable deviations in pulsar timings. We demonstrate that dark matter models predicting enhanced power on small scales (< pc) are potentially within the reach of future PTA experiments, such as the Square Kilometer Array (SKA). This includes a class of post-inflationary QCD axion models known as axion miniclusters. We also discuss pipelines for searching for dark matter signals in PTA datasets and recent results from the 15-year data release of the North American Nanohertz Observatory for Gravitational Waves (NANOGrav), which has reported evidence of a stochastic gravitational background. Furthermore, dark matter particles with a mass on the kilogram scale can also produce signals in laser interferometry-based gravitational wave experiments. We discuss the signals and detection prospects from current and future gravitational wave experiments, such as LIGO and the Einstein Telescope. Event recording:
- Host: Joshua Foster