Skip to Content

Colloquium

« Previous Page  Page 2 of 15  Next Page »
January 26, 2018

Exploring Quantum Measurement with Nanomechanics and Light

Date:  Thursday,  February 1, 2018

Speaker:  Dalziel Wilson, IBM Research, Zurich 

Abstract: 

Nanomechanical resonators are exquisite force sensors.  In a new generation of experiments, they have even been used to “feel” the vacuum fluctuations of a laser field.  This talk addresses the opposite side of the coin: can the same laser be used to “see” the vacuum fluctuations of the nanomechanical resonator?  If so, can such a measurement be leveraged to cool a tangibly-sized mechanical object to its ground state, using feedback?  I will describe an experiment designed to achieve both goals, based on a nanostring coupled to an optical microcavity.  Along the way, I will show how this system can realize a position measurement with an imprecision 40 dB below that at the standard quantum limit, and “erase” part of the ensuing back-action using quantum noise correlations (a strategy of interest for future LIGO). I will also briefly describe a new class of nanomechanical resonators with room temperature quality factors exceeding 100 million. These devices undergo 100s of coherent oscillations before interacting with the thermal environment, and may enable new optomechanics-based quantum technologies.

References:

  1. D. Wilson et. al., Nature 524, 325 (2015) 2. R. Schilling et. al., Phys. Rev. App. 5, 054019 (2016) 3. V. Sudhir et. al., Phys. Rev. X 7, 011001 (2017) 4. V. Sudhir et. al., Phys. Rev. X 7 (3), 031055 (2017) 5. A. Ghadimi et. al., arXiv:1711.06247 (2017)

Host:  Mike Raymer

Catered Reception: 3:40pm-3:55pm, Willamette Hall, Paul Olum Atrium

Colloquium Preview

Colloquium Archive

January 19, 2018

Entangling Trapped Ions with a Low-Frequency Magnetic Field Gradient

Date:  Thursday,  January 25, 2018

Speaker:  David Allcock, NIST

Abstract: 

Entangled states of trapped ions are typically generated using laser-induced spin-motion coupling. Spin-motion coupling with hyperfine qubits has also been demonstrated with microwave magnetic fields instead of lasers, thus eliminating photon scattering errors and offering potential benefits for scalability. These experiments have relied on either static magnetic field gradients or oscillating magnetic field gradients at GHz frequencies [1-4]. We present methods of spin-motion coupling using magnetic field gradients oscillating at MHz frequencies. We entangle the internal states of two trapped 25Mg+ ions in a cryogenic microfabricated surface-electrode trap and characterize the Bell-state fidelity. These implementations offer important technical advantages over both the static-gradient and GHz-gradient techniques.

[1] Mintert and Wunderlich PRL 87, 257904 (2001)
[2] Weidt et al. PRL 117, 220501 (2016)
[3] Ospelkaus et al. Nature 476, 181 (2011)
[4] Harty et al. PRL 117, 140501 (2016)

Host:  Mike Raymer

Catered Reception: 3:40pm-3:55pm, Willamette Hall, Paul Olum Atrium

Colloquium Preview

Colloquium Archive

January 12, 2018

Quantum Acoustics with Superconducting Qubits

Date:  Thursday,  January 18, 2018

Speaker:  Yiwen Chu, Yale University

Abstract:  The ability to engineer and manipulate different types of quantum mechanical objects allows us to take advantage of their unique properties and create useful hybrid technologies. Thus far, complex quantum states and exquisite quantum control have been demonstrated in systems ranging from trapped ions to superconducting resonators. Recently, there have been many efforts to extend these demonstrations to the motion of complex, macroscopic objects. These mechanical objects have important applications as quantum memories or transducers for measuring and connecting different types of quantum systems. In particular, there have been a few experiments that couple motion to nonlinear quantum objects such as superconducting qubits. This opens up the possibility of creating, storing, and manipulating non-Gaussian quantum states in mechanical degrees of freedom. However, before sophisticated quantum control of mechanical motion can be achieved, we must realize systems with long coherence times while maintaining a sufficient interaction strength. These systems should be implemented in a simple and robust manner that allows for increasing complexity and scalability in the future.

In this talk, I will describe our recent experiments demonstrating a high frequency bulk acoustic wave resonator that is strongly coupled to a superconducting qubit using piezoelectric transduction. Our device requires only simple fabrication methods, extends coherence times to many microseconds, and provides controllable access to a multitude of phonon modes. We use this system to demonstrate basic quantum operations on the coupled qubit-phonon system. I will also briefly describe our current efforts to further improve our electromechanical device, which will hopefully allow for advanced quantum protocols analogous to what has been shown in optical and microwave resonators, resulting in a novel resource for implementing hybrid quantum technologies.

Host:  Mike Raymer

Catered Reception: 3:40pm-3:55pm, Willamette Hall, Paul Olum Atrium

Colloquium Preview

Colloquium Archive

January 9, 2018

Blending Teaching, Outreach, and Research into an Astronomical Amalgam

Date:  Thursday,  January 11, 2018

Speaker:  Scott Fisher, UO

Abstract:

In this colloquium Scott Fisher will present on his work in the Department of Physics. Different than a typical research presentation, in this talk Scott will describe his efforts in the realms of teaching, outreach, and research and show how he has blended these topics into a vibrant and fulfilling position within UO Physics. He will give an overview of his teaching (and outreach) style and discuss a few in class (and speaking to the public) techniques used in his general education ASTR-12x classes and public/K-12 programs. With respect to research, he will give a top-level overview of research activities, including a discussion of ongoing and future projects at Pine Mountain Observatory as well as a discussion of a recent publication on Galaxy Evolution. In particular he will highlight the work done by a team of undergraduate PHYS majors which led to an extremely rare first-author publication for one of our students.

 

Host:  Mike Raymer

Catered Reception: 3:40pm-3:55pm, Willamette Hall, Paul Olum Atrium

Colloquium Preview

Colloquium Archive

January 5, 2018

Scott Fisher, UO

Date: 1/11/2018

Speaker: Scott Fisher, University of Oregon

Title: TBA

Abstract: TBA

Time:4:00-5:00pm


Location: 100 Willamette Hall

Host: Mike Raymer

 

Colloquium Preview

Colloquium Archive

 

December 1, 2017

Happy Holidays

The Physics colloquium series will resume after winter break.

 

November 21, 2017

GW170817: Astronomy’s First Talkie

Date:  Thursday, November 30th, 2017

Speaker: Ben Farr, UO Physics

Abstract:

On August 25, 2017, after collecting 117 days of simultaneous two-detector observing time, the LIGO observatories ended their second observing run (O2).  Having started on November 30, 2016, O2 had progressed relatively uneventfully for 260 calendar days. That is, until August 17, 2017, when LIGO detected its first binary neutron star merger, GW170817. Beyond being LIGO’s first binary neutron star detection, and its longest and loudest detection so far, it was also detected by telescopes across the entire electromagnetic spectrum, emphatically kicking off the era of multi-messenger astronomy using gravitational waves.  With more than 70 ground- and space-based observatories joining in the discovery, GW170817 quickly became one of the most observed transients in the history of astronomy.  I will discuss some of what GW170817 and its EM counterpart, particularly its kilonova signature, has taught us (so far) about neutron star collisions, the expansion of the universe, and fundamental physics.

Host:  Ray Frey

Time: 4:00-5:00pm
Location: 100 Willamette Hall
Reception from 3:40-3:55 Willamette Hall Paul Olum Atrium

Colloquium Preview

Colloquium Archive

November 17, 2017

Happy Thanksgiving

The Physics colloquium series will resume on Thursday, November 30th 2017 with presentation by UO Physics professor Ben Farr.

November 10, 2017

Flashes of Hidden Worlds at Colliders

Date:  Thursday, November 16th, 2017

Speaker: David Curtin, University of Toronto

Abstract:  After briefly reviewing the Standard Model of particle physics, I explain why the fundamental reasons to expect New Physics are more urgent than ever. Null results of searches at the Large Hadron Collider (LHC) and other experiments are therefore especially puzzling. I argue that this points us towards new theories for addressing these fundamental mysteries, and new experimental approaches for discovering them. I will discuss how theories of Hidden Sectors can address the Hierarchy Problem, the universe’s matter-antimatter asymmetry, and Dark Matter. I outline why these scenarios could have gone undiscovered so far, but also why their hidden nature is also the key to their discovery, since they give rise to the production of exotic Long-Lived Particles (LLPs) at the LHC. Exploring this Lifetime Frontier requires a new systematic search program, as well as new detectors. Our proposed MATHUSLA experiment will boost the sensitivity of the HL-LHC by orders of magnitude.

Host:  Tim Cohen

Time: 4:00-5:00pm
Location: 100 Willamette Hall
Reception from 3:40-3:55 Willamette Hall Paul Olum Atrium

Colloquium Preview

Colloquium Archive

November 3, 2017

Unstructured Proteins: Extracting Function from Disorder

Date:  Thursday, November 9th, 2017

Speaker:  Ajay Gopinathan, UC Merced

Abstract:

Intrinsically unstructured or disordered proteins (IDPs), which form over a third of human proteins, challenge the structure-function paradigm in biology that relates the function of proteins to their unique 3-d structure, because they function without ever folding into a unique structure. This presents an interesting opportunity to use the tools of polymer physics to gain insight into IDP dynamics and function. I shall present an overview of IDPs and a couple of examples of our recent efforts to understand how IDPs can exploit conformational entropy for functional purposes. One particularly fascinating context for IDP function is the nuclear pore complex (NPC) which gates nanoscale pores in the nuclear envelope of cells. The NPC controls all traffic into and out of the nucleus using a barrier composed of a large number of IDPs that fill the pore. Despite numerous studies, the actual structure of the barrier and its mechanism of operation are poorly understood primarily because of the disordered nature of these proteins. Here, I will present our “bottom-up” approach using sequence analysis, coarse-grained simulations and polymer brush theory which points to a novel form of gated transport in operation within the nuclear pore complex based on polymer brush physics. Another striking example of the use of conformational entropy is in the translocation across the cell wall of certain bacterial IDPs. I will present evidence that this translocation depends only on cell geometry and protein length indicating that bacteria can exploit purely physical entropic mechanisms to perform this function.

Host: Raghu Parthasarathy

Time: 4:00-5:00pm
Location: 100 Willamette Hall
Reception from 3:40-3:55 Willamette Hall Paul Olum Atrium

Colloquium Preview

Colloquium Archive

« Previous Page  Page 2 of 15  Next Page »