Events - Weekly
|Sunday, December 8|
|Monday, December 9|
Biophysics Seminar Series - Zvonimir Dogic (Brandeis )
"Cluster crystals and other surprises in the flatland."
Jadwin 111 · 12:00 p.m.– 1:00 p.m.
Condensed Matter Seminar, Waseem Bakr, "Synthetic condensed matter systems with ultracold atoms"
Recent advances in preparing, probing and manipulating ultracold atomic gases enable studying condensed matter physics in a very controlled setting. In the first part of my talk, I will describe quantum gas microscopy, a powerful tool for imaging and manipulating strongly interacting quantum gases containing thousands of atoms at the single atom level. I will describe its application to studying quantum phase transitions of Mott insulators and quantum magnets in bosonic systems of atoms.
In the second part of the talk, I will shift focus to topological physics in fermionic systems. I will explain how spin-orbit coupling, a crucial ingredient of time-reversal invariant topological insulators, can be engineered in a Fermi gas by dressing it with laser light. In addition, I will present results on strongly interacting fermions in two dimensions. These two ingredients can be combined to create topological superfluids analogous to topological superconductors that have been possibly realized in the solid state. Finally, I conclude with a brief outlook on experiments starting at Princeton with the goal of studying Chern insulators in optical lattices.
PCTS Seminar Room · 1:15 p.m.– 2:30 p.m.
High Energy Theory Seminar - Liam McAllister, Cornell University - "The Wasteland of Random Supergravities"
I will present results on the statistics of metastable vacua in string theory. Standard counts of string vacua, including the celebrated estimate of >10^500 flux vacua in type IIB string theory, do not incorporate the constraint of metastability, and therefore effectively count the combined number of maxima, minima, and unstable saddle points. We show that in general N=1 supergravity theories with N >> 1 scalar fields, metastability is an extremely strong constraint: the probability that a generic critical point is a metastable minimum, rather than an unstable saddle, is exp(-c N^2), for a constant c. Even approximately-supersymmetric critical points are overwhelmingly likely to be unstable, with positivity probability exp(-d N). We arrive at these results by deriving a random matrix model for the Hessian in supergravity and computing its spectrum analytically. Our findings have significant implications for the counting of de Sitter vacua in string theory, but the number of vacua remains vast.
PCTS Seminar Room · 2:30 p.m.– 3:30 p.m.
|Tuesday, December 10|
Quantum Sciences Seminar - Christopher Eichler, ETH Zurich - "Exploring quantum microwave radiation emitted from superconducting electronic circuits."
Superconducting electronic circuits have turned into one of the prime physical systems to investigate quantum optical and atomic physics phenomena in engineered solid state devices. While the on-demand generation and the processing of quantum states on a chip are now routinely achieved with high fidelity, it remains challenging to detect propagating microwave photons with equally high efficiency. This is mainly due to the absence of efficient photon counters in this frequency range. In my presentation, I explain how we employ low-noise linear amplifiers instead of photon counters for measuring microwave field correlations at the quantum level. For this purpose we have developed efficient data acquisition, processing and analysis techniques to separate the quantum signal of interest from the noise added by the amplifiers . In our experiments we have successfully generated and characterized various types of interesting quantum fields, ranging from on-demand single photons , over squeezed radiation , to spatially entangled fields . Recently, we have also developed our own parametric amplifiers to perform nearly quantum limited measurements of microwave radiation [3,6]. These enabled us to observe entanglement between a quantum two-level system and microwave photons propagating freely through a transmission line . The possibility to accurately synthesize, guide and characterize non-classical microwave fields bears great potential to be used in radiation based quantum simulation and quantum network architectures and for probing other systems with yet unrivaled sensitivity.
 C. Eichler et al., PRA 86, 032106–13 (2012),  C. Eichler et al., PRL. 106, 220503 (2011),  C. Eichler et al., PRL 107, 113601 (2011),  C. Lang et al. Nat. Phys., in print (2013),  C. Eichler et al., PRL. 109, 240501 (2012),  C. Eichler and A. Wallraff, arXiv:1305.6583
PCTS Seminar Room · 1:00 p.m.– 2:00 p.m.
|Wednesday, December 11|
Quantum Sciences Seminar Series - Yuimaru Kubo, CEA-Saclay – “Hybrid Quantum Circuit with a Superconducting Qubit and an Electron Spin Ensemble”
We report the experimental realization of a hybrid quantum circuit combining a superconducting qubit and an ensemble of electronic spins (Fig. a). The qubit, of the transmon type, is coherently coupled to the spin ensemble consisting of nitrogen-vacancy (NV) centers in a diamond crystal via a frequency-tunable superconducting resonator acting as a quantum bus [1,2]. Using this circuit, we prepare arbitrary superpositions of the qubit states that we store into collective excitations of the spin ensemble and retrieve back into the qubit later on (Fig. b) . These results constitute a first proof of concept of spin-ensemble based quantum memory for superconducting qubits.
We also report a new method for detecting the magnetic resonance of electronic spins at low temperature with a qubit using the hybrid quantum circuit .
 Y. Kubo et al., Phys. Rev. Lett., 105, 140502 (2010).
 Y. Kubo et al., Phys. Rev. A, 85, 012333 (2012).
 Y. Kubo et al., Phys. Rev. Lett., 107, 220501 (2011).
 Y. Kubo et al., Phys. Rev. B, 86, 064514 (2012).
Joseph Henry Room · 12:30 p.m.– 1:30 p.m.
|Thursday, December 12|
Dicke Fellowship Seminar, Merideth Frey, "Citius, Altius, Fortius – The Quest for Faster Imaging, Higher Resolution, and Stronger Signal in MRI . .
Magnetic resonance techniques have proven to be extremely useful in nearly every scientific discipline, from controlling spin dynamics in condensed matter physics to imaging diseased tissue in biomedical engineering. In the first part of my talk, I will discuss my doctoral work implementing a novel spin-control pulse sequence that overcame well-known barriers to high-resolution MRI of solids, dominated by the need for faster imaging, higher resolution, and stronger signal. My results include the highest resolution MRI of phosphorus (P-31) in bone mineral, the first 3D image of P-31 in an organ where the signal comes predominately from phospholipid membranes, and a reconstruction algorithm that speeds up imaging significantly without cost to image quality. In the last part of my talk, I will discuss my plans to continue expanding beyond conventional magnetic resonance techniques to make use of low-field NMR and sensitive atomic magnetometers as detectors.
Jadwin 303 · 3:00 p.m.– 4:30 p.m.
|Friday, December 13|
High Energy Theory Seminar - IAS - Ben Safdi, Princeton University - “New Predictions for Dark-Matter Direct-Detection Experiments”
Bloomberg Lecture Hall - Institute for Advanced Study · 1:30 p.m.– 2:30 p.m.
|Saturday, December 14|