Bulletin of the American Physical Society
2017 Annual Meeting of the Far West Section
Friday–Saturday, November 3–4, 2017; Merced, California
Session D1: Saturday Plenary |
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Chair: Andreas Bill, Cal State University Long Beach Room: COB1 120 |
Saturday, November 4, 2017 9:00AM - 9:36AM |
D1.00001: Hunting for dark matter with GPS and atomic clocks Invited Speaker: Andrei Derevianko Atomic clocks are arguably the most accurate scientific instruments ever build. Modern clocks are astonishing timepieces guaranteed~to~keep time within a second over the age of the Universe.~~Attaining this accuracy requires that the quantum oscillator be well protected from environmental noise and that clock perturbations be well controlled and characterized. This opens intriguing prospects of using clocks to study subtle effects, and it is natural to ask if such accuracy can be harnessed for dark matter searches. The cosmological applications of atomic clocks so far have been limited to searches of the uniform-in-time drift of fundamental constants. We point out that a transient in time change of fundamental constants can be induced by dark matter objects that have large spatial extent, and are built from light non-Standard Model fields. A correlated network~of atomic clocks, such as atomic clocks onboard satellites of the GPS constellation, can be used as a tool to search for ``clumpy'' dark matter. I will present initial results of our dark matter search with archival GPS data. [Preview Abstract] |
Saturday, November 4, 2017 9:36AM - 10:12AM |
D1.00002: Amorphous Materials: Exotic Physics and Practical Applications Arising from Disorder Invited Speaker: Frances Hellman Virtually all textbooks of solid state physics start from the premise of a perfect crystal, from which the properties and characteristics of the material are derived, such as electrical resistance, superconductivity, optical properties, etc. Yet, few real materials have that perfect crystal structure, and in many cases the disorder actually improves the properties, sometimes significantly. Disorder comes in different forms: structural or chemical defects, grain boundaries, even surfaces. In some cases, the structural disorder is so strong that it is impossible to consider the disorder in terms of defects, and the material is called amorphous. This is for example the state that is created by rapidly quenching a liquid such as molten silicon dioxide, which is the basis for window glass. It is also possible to create amorphous or glassy materials by vapor deposition techniques, and in some particular cases, to create a disordered material that has low entropy and enthalpy, much like a crystal has. This is partially because the material can have short or even medium range order, without having long range order. Superconductivity is an example of an exotic property that can arise in an amorphous material, despite the fact that the original theory of superconductivity relied on crystalline symmetry. Other examples exist, some with very practical applications, and these challenge both theorists and experimentalists to think more deeply about the underlying physics of the phenomenon they are describing, and not to only rely on the simpler mathematics of the crystalline structure. [Preview Abstract] |
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