Events at Physics
Events on Thursday, May 15th, 2014
- R. G. Herb Condensed Matter Seminar
- Realization of a Single-Cooper-Pair Josephson Laser
- Time: 10:00 am
- Place: 5310 Chamberlin Hall
- Speaker: Alex Rimberg, Dartmouth
- Abstract: The non-linear interaction of light with matter, long studied in the context of atomic systems, has recently been extended to condensed matter systems through the advent of quantum optical experiments based on superconducting circuits. Application of quantum optical techniques in this context has led to new regimes of ultrastrong coupling between light and matter, manipulation and readout of qubits, generation of quantum states of light and development of ultra-low-noise quantum amplifiers. A particularly familiar application of quantum optics is the laser, which in the single emitter regime has in atomic systems led to the production of pure photon number states and sub-Poissonian photon statistics. We have recently produced a device consisting of a Cooper pair transistor embedded in a high-Q superconducting microwave cavity (cCPT) that acts as a single emitter laser and may offer a path toward simple, continual production of non-classical photons. Similar devices may also allow for ultrastrong coupling of microwave photons to other quantum systems such as spin qubits and nanomechanical resonators.
- Host: Eriksson
- Special Talk
- Calibrating the radio continuum-star formation relation in WSRT SINGS galaxies
- Time: 3:30 pm
- Place: 4421 Sterling Hall
- Speaker: Volker Heesen, University of Southhampton
- Abstract: Radio continuum (RC) emission holds the promise of being an accurate because unobscured tracer for star formation (SF), allowing us to measure the evolution of the Cosmic star formation rate (SFR) in dusty high-z galaxies. We use WSRT RC observations at 22 cm and state-of-the-art hybrid SFR density maps, combining GALEX FUV data, tracing un-obscured SF, and Spitzer 24 mu data, tracing SF embedded in dust. With these data we calibrate the well-known RC-SFR relation as proposed by Condon (1992) on a spatially resolved basis in a sample of 17 nearby galaxies. We find that for integrated measurements Condon's relation works quite well: the absolute value of the RC derived SFR is in agreement with the hybrid SFR, and the RC-SFR relation is almost linear with RC ~ SFRD^(1.11pm0.05). The same holds true for azimuthally averaged data, where the ratio of RC to hybrid derived SFR density is almost constant with only quasi-periodic fluctuations of 25% amplitude. The spatially resolved data, however, shows that on a 1 kpc scale the RC-SFR relation is sub-linear, which we attribute largely to the effect of cosmic-ray transport. We study the dependence of the RC-SFR relation on various galaxy parameters and find none, meaning that the RC-SFR relation is universal.
- Host: Professor and Dept Chair, Ellen Zweibel