Research Projects in Physics and Biophysics, Lecture notes of Solid State Physics

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This is a highlights/sampling. One person -> mul6ple areas, One project -> mul6ple PIs. Collabs between dept members. Collabs across campus. Na6onal and interna6onal collabs. You’ll get to talk to experts during the day about the topics you are most interested in.

Working on using ions as qubits for quantum informa6on science. 2 internal states are the 0 and the 1. With precise laser fields, can address, prepare and manipulate these qubits. Working on scaling up qubit number with mul6ple ion traps on a chip.

Gupta group is pursuing experiments with quantum degenerate gases of bosonic and fermionic atoms. Realized at ultra-low nanoKelvin temperature and ultra-low density (million 6mes thinner than air), these systems are theore6cally tractable and experimentally controllable with precision AMO tools (lasers, EM fields). The gases are prepared in ultra-high vacuum using laser cooling (see photo – green blob in middle is a cloud of fluorescing laser cooled atoms inside the vacuum chamber. About 1 billion Yb atoms at 100 microKelvin) and evapora6ve cooling. We are preparing and exploring synthe6c quantum maYer to understand complex many-body phenomena (such as high-Tc superconduc6vity and double superfluidity) and for engineering tools for quantum informa6on science, such as dipolar molecules trapped in an op6cal laZce. We are also using Bose-Einstein condensates (BECs, or atom lasers) for precision interferometry and tests of fundamental physics such as the theory of quantum electrodynamics.

We are interested in watching biological processes happen inside cells one at a 6me. The slides shows the first visualiza6on of a "replica6on conflict" in which the replica6on machinery falls off the DNA during the replica6on process.

We study a wide variety of physics in nanoscale systems. Here are a few examples: Top leb: these sharp spikes occur at liquid helium temperatures in carbon nanotube transistors. Each corresponds to adding a single electronic charge to the near-perfect one-dimensional quantum dot formed in the nanotube. Top right: a solid-state phase transi6on between an insula6ng and a metallic phase is studied in a suspended vanadium dioxide nanobeam op6cally and electrically. Above is a simple op6cal image, below is an image of the current generated in the contacts as a laser is swept over the devices. We find that photocurrent is generated only near the interface between the two phases. BoYom leb: a phase transi6on is studied occurring amongst Kr atoms stuck to the surface of a single nanotube, which vibrates like a nanoguitar. The frequency change tells us the density of atoms, and the electrical conductance also changes. BoYom right: We have a growing effort in 2d materials beyond graphene – including 2D semimetals which may have nontrivial electron topology (leb), and 2D semiconductors – see for example this transmisision electron microscopy image (right) of an in-plane junc6on we grew between two different semiconductors in a single atomic layer.

My lab studies quantum materials. These are materials in which the quantum effect

plays a major role, and very oben there is no semi-classical analogue. Here are two

examples. The first one is iron arsenide high temperature superconductors. In this

material the superconduc6vity is believed to be closely related to the quantum

fluctua6ons of a quantum cri6cal point. The quantum fluctua6ons can be detected,

for example, by the degree of electronic anisotropy induced by strain, indicated by

the color map in the phase diagram.

Another example is topological insulator. In this case because of the quantum

mechanical spin-orbit coupling effect, Dirac-like electrons emerge on the surface of

this insulator. The energy momentum rela6ons can be directly measured by photo-

emission, and a non-trivial Berry phase can be detected by quantum oscilla6ons of

resistance.

Kai-Mei Fu’s lab bridges atomic physics and condensed maYer physics. We engineer solid- state impurity systems to have “atom-like” proper6es. We then take advantage of the addi6onal func6onality of the solid-state plagorm to integrate the impuri6es into nanoscale devices. This enables us to study and control photon-spin interac6ons and also to link spins through on-chip op6cal networks. The applica6ons of this work range from large-scale quantum informa6on processing to magne6c sensing. (In this slide GaAs = gallium arsenide)

Li group is joint with the ECE and Physics department. The group works on hybrid integrated photonic devices and systems based on a variety of materials. They study interac6on between the mechanical mo6on (vibra6ons, sound waves) with light in optomechanical systems and pursue their quantum informa6on applica6ons. They integrate 2D, magne6c and quantum materials with integrated photonic circuits to realize novel optoelectronic and spintronic devices. They aslo develop applica6on tools for neuroscience and biomolecule sensing.

The Seidler group specializes in the development and use of advanced x-ray spectroscopies. In our technology development, we’ve been leading a worldwide effort to find ways to do these x-ray spectroscopies in the lab, without needing to go to a synchrotron light source. This allows us tremendous freedom to find new science and work in new sub-fields. Recent examples are in forensic science, regulatory and public health tes6ng, new materials for use in lithium ion baYeries or in energy efficiency LED screens, and also seeking to understand the property of maYer inside gas giant planets or under dense stellar condi6ons. Please visit our lab on the second floor of PAB, room 228.

1. The current comparison of muon g-2 between theory and experiment has a 3.6 sigma discrepancy, one of the strongest hints of new physics in all of physics
2. We at UW are co-leading a major new experiment to improve the precision to 140 ppb, a factor 4 or more beYer; This leads to "discovery" poten6al, which is > 5 sigma
3. They are running now in a first "physics / commissioning" run this spring and will con6nue to operate for next 3 or more years
4. UW has a) built the major detector system to measure the muon spin precession frequency b) built the NMR probes, their electronics, and their DAQ to measure the magne6c field c) carried out the muon storage simula6on and built imaging detectors d) developed the analysis and calibra6on sobware e) designed the overall Offline analysis framework related to the spin precession measurement f) many people in leadership posi6ons in collab of 150 from 35 ins6tutes We are the largest team in the collabora6on, apart from Fermilab itself.

When neutrinos were found to have mass, it opened the possibility that they could be Majorana fermions. Majorana neutrinos are a “predic6on” of many grand unifica6on theories and of leptogenesis, which can explain the predominance of maYer in our universe but requires maYer-crea6ng processes involving leptons like neutrinoless double-beta decay. Detwiler’s group is pursuing searches for this ultra-rare process, with data coming in now from Majorana, and R&D underway for it’s follow-on project LEGEND. Top picture: 1st^ Majorana detector array ready for deployment. Pic taken inside the glovebox (glovebox protects the detectors from dust and radon). The copper is the cleanest (most radiopure) copper known to man (10s of ppq max for U and Th), grown underground right down the hall from the experiment. Below that: the liquid argon cryostat at Gran Sasso, Italy that will house LEGEND 200, and a conceptual drawing of the 1-ton version of this experiment. BoYom center plot: Majorana’s measured spectrum, from our recently accepted PRL. Data is aber all cuts. Black is early high-background data, red is the clean stuff. The blue region in the inset is where we would see 0nbb, we see nothing yet. BoYom lebplot – first observa6on of coherent elas6c neutrino nuclear scaYering with a CsI detector at the SNS (COHERENT). Got the cover of Science last August, runner-up for discovery of the year.

1. We are con6nuing the effort to determine the e-nu correla6on from laser-trapped 6He. We expect to have our first results within a years 6me. Further improvements in the setup could yield much improvements in the future.
2. We are working on using the technique developed by the Project8 fellows to the detec6on of the 6He beta spectrum. If all works as in paper this will be about 1 order of magnitude than experiments at the LHC searching for the same physics.