Atomic Physics Seminar

In the last decades, advances in the level of precision in controlling atomic and optical systems opened up the low-energy precision frontier to fundamental physics tests in addition to yielding new applied sensing technologies. In this talk I will focus on our experiments with cold atoms highlighting some of the most recent developments in the prospect of using quantum entanglement to further improve the precision of atomic and optical sensors.
I will describe the generation of 20dB spin-squeezed states of half a million 87Rb atoms inside of an optical cavity. From a practical point of view, the generated states enable up to a 100-fold reduction in required averaging times or atom numbers to achieve a given precision. I will explain the implementation of an atomic clock operating 10 dB beyond the standard quantum limit as well as the investigations of entanglement and Bell correlations in this system. I will then describe the demonstration of a new concept we call quantum phase magnification which utilizes optical cavity-aided interactions between atoms to magnify signals to-be-measured. This technique eliminates the need for low noise detection to achieve phase sensitivities beyond the standard quantum limit. I will conclude with future visions.
Host: 
Thad Walker
Speaker: Onur Hosten stanford

 

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Room and Building: 
5310 Chamberlin Hall

Polar molecules offer long-range anisotropic interactions, which are fundamental to a wide variety of phenomena, from ferrofluid behavior to the folding of proteins. Recent demonstrations of cooling and trapping polar molecules have made it possible to study these particles in the quantum regime, making them highly attractive for applications such as quantum information storage and exploring novel condensed matter phases. In this talk, I will report on the quantum control of dipolar fermionic NaK molecules, which we have synthesized in the ground state at ultracold temperatures as low as 300 nK. Using microwaves, we have coherently manipulated not only the rotational states of the molecules, but also the nuclear spin degree of freedom. I will present our observation of nuclear spin coherence times on the scale of 1 second, and discuss its implications for quantum memory and probing new physics via Hertz-level precision spectroscopy.

Host: 
Thad Walker
Speaker: Huanqian Loh MIT

 

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Room and Building: 
5280 Chamberlin Hall

High energy short pulse lasers are useful tools for probing the structure and dynamics of materials and accelerating particles. The European Union is investing in a network of laser centers focused on fundamental research called the Extreme Light Infrastructure (ELI). ELI hopes to allow the investigation of new regimes of laser-matter interaction with multi-petawatt laser pulses and unprecedented repetition rates. In this talk I will present one of the facilities currently under development in Prague, Czech Republic. While an overview of the laser systems under development will be given, the primary focus of the talk will be on current techniques and principles of high energy laser amplification.

Host: 
Yavuz
Speaker: Tyler Green ELI project at the Czech Republic.

 

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Room and Building: 
5310 Chamberlin Hall

Optical atomic magnetometers are among the most precise magnetic sensors today, reaching sensitivities up to 0.16 fT/sqrt(Hz). While the AC Stark effect is one of the noise sources in atomic magnetometers, it can be utilized to improve these devices. The effect of the vector part of the AC Stark operator on alkali atoms is equivalent to applying a magnetic field in the direction of the light propagation. We use this effect to create an all-optical vector magnetometer with 0.2 pT/sqrt(Hz) sensitivity to the field magnitude and 4 mrad/sqrt(Hz) sensitivity to the field direction, as well as a scalar magnetometer driven by a fictitious rf field with 40 fT/sqrt(Hz) sensitivity.

Host: 
Walker
Speaker: Lena Zhivun Berkeley

 

Available Downloads:

Room and Building: 
5310 Chamberlin

TBD

Host: 
Walker
Speaker: Dr. Stephen Kadlecek University of Pennsylvania

 

Available Downloads:

Room and Building: 
5280 Chamberlin Hall

Atomic Hong-Ou-Mandel effect: a mile-stone in Quantum Atom Optics

Host: 
Walker
Speaker: Alain Aspect Institut d’Optique

 

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Room and Building: 
5310 Chamberlin Hall
An alternative framework to quantum information and computation based on spin coherent states is proposed. Traditionally quantum computing approaches are formulated in terms of either discrete (qubit) or continuous variables. Our approach offers an alternative third path, naturally suited towards implementations in cold atom ensembles and BECs. The scheme is illustrated by an application to quantum algorithms and we discuss the effects of decoherence induced by the large number of particles in the BEC. In particular, we discuss a quantum teleportation protocol that allows for the transfer of spin coherent states beyond the usual continuous variables formalism. The scheme differs from existing protocols in that a large ensemble of spins is teleported, rather than a qubit variable, resulting in a type of macroscopic teleportation. Other techniques such as phase contrast imaging and Deutsch-Jozsa algorithm in a beyond continuous variables context are also discussed.
Host: 
Saffman
Speaker: Tim Byrnes NYU

 

Available Downloads:

Room and Building: 
5310 Chamberlin
Host: 
Yavuz
Speaker: various various

 

Available Downloads:

Room and Building: 
2241 Chamberlin Hall
Photons are the perfect "flying qubits" for quantum communication: they travel at the speed of light and have only weak nonlinear interactions with their environment. While these features make photons ideal carriers of quantum information, many quantum communication protocols require qubits to interact in quantum logic gates. Although interactions between individual photons are too weak for reliable multi-qubit gates, it is relatively easy to implement efficient gates between different degrees of freedom encoded on the same photon. By using photons that are simultaneously entangled in multiple degrees of freedom ("hyperentangled") we can perform operations that are impossible for single-qubit states, as well as gain access to higher dimensional entanglement. We demonstrate that hyperentangled states can be used for efficient quantum state communication, increased classical channel capacity, and more efficient quantum channel characterization.
Host: 
Saffman
Speaker: Trent Graham Urbana-Champaign

 

Available Downloads:

Room and Building: 
5310 Chamberlin Hall

Coulomb interactions limit the brightness of charged particle beams. Controlling the effects of nonlinear beam expansion (space charge) and disordered inter-particle scattering is of critical importance for applications ranging from ultrafast electron diffraction to injectors for particle accelerators. In this talk I will show that ultra-cold ion bunches extracted from laser-cooled atoms can be used to observe the effects of Coulomb interactions with unprecedented detail. Arbitrarily shaped bunches are created to reverse the space-charge problem, and excitation of the cold atoms to Rydberg states prior to ionisation reduces the disorder-induced heating effect. I will present our experimental results that demonstrate improved beam brightness and models and simulations of the effects.

Host: 
Saffman
Speaker: Dene Murphy University Melbourne

 

Available Downloads:

Room and Building: 
5310 Chamberlin Hall

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