Department of Physics
http://hdl.handle.net/1957/13831
Fri, 01 Aug 2014 14:09:51 GMT2014-08-01T14:09:51ZName the experiment! Interpreting thermodynamic derivatives as thought experiments
http://hdl.handle.net/1957/49915
Name the experiment! Interpreting thermodynamic derivatives as thought experiments
Roundy, David; Kustusch, Mary Bridget; Manogue, Corinne
We introduce a series of activities to help students understand the partial derivatives that arise in thermodynamics. Students construct thought experiments that would allow them to measure given partial derivatives. These activities are constructed with a number of learning goals in mind, beginning with helping students to learn to think of thermodynamic quantities in terms of how one can measure or change them. A second learning goal is for students to understand the importance of the quantities held fixed in either a partial derivative or an experiment. Students additionally are given an experimental perspective—particularly when this activity is combined with real laboratory experiments—on the meaning of either fixing or changing entropy. In this paper, we introduce the activities and explain their learning goals. We also include examples of student work from classroom video and follow-up interviews.
This is an author's peer-reviewed final manuscript, as accepted by the publisher. The article is published by the American Association of Physics Teachers and can be found at: http://scitation.aip.org/content/aapt/journal/ajp.
Wed, 01 Jan 2014 00:00:00 GMThttp://hdl.handle.net/1957/499152014-01-01T00:00:00ZAmplification, Redundancy, and Quantum Chernoff Information
http://hdl.handle.net/1957/49806
Amplification, Redundancy, and Quantum Chernoff Information
Zwolak, Michael; Riedel, C. Jess; Zurek, Wojciech H.
Amplification was regarded, since the early days of quantum theory, as a mysterious ingredient that
endows quantum microstates with macroscopic consequences, key to the “collapse of the wave packet,”
and a way to avoid embarrassing problems exemplified by Schrödinger’s cat. Such a bridge between the
quantum microworld and the classical world of our experience was postulated ad hoc in the Copenhagen
interpretation. Quantum Darwinism views amplification as replication, in many copies, of the information
about quantum states. We show that such amplification is a natural consequence of a broad class of models
of decoherence, including the photon environment we use to obtain most of our information. This leads
to objective reality via the presence of robust and widely accessible records of selected quantum states.
The resulting redundancy (the number of copies deposited in the environment) follows from the quantum
Chernoff information that quantifies the information transmitted by a typical elementary subsystem of the
environment.
This is the publisher’s final pdf. The published article is copyrighted by the American Physical Society and can be found at: http://journals.aps.org/prl/.
Fri, 11 Apr 2014 00:00:00 GMThttp://hdl.handle.net/1957/498062014-04-11T00:00:00ZRecurrent construction of optimal entanglement witnesses for 2N-qubit systems
http://hdl.handle.net/1957/49001
Recurrent construction of optimal entanglement witnesses for 2N-qubit systems
Zwolak, Justyna P.; Chruściński, Dariusz
We provide a recurrent construction of entanglement witnesses for a bipartite systems living in a Hilbert space
corresponding to 2N qubits (N qubits in each subsystem). Our construction provides a method of generalization
of the Robertson map that naturally meshes with 2N-qubit systems, i.e., its structure respects the 2[superscript 2N] growth of
the state space. We prove that for N>1 these witnesses are indecomposable and optimal. As a byproduct we
provide a family of PPT (Positive Partial Transpose) entangled states.
This is the publisher’s final pdf. The published article is copyrighted by the American Physical Society and can be found at: https://journals.aps.org/pra/.
Mon, 12 May 2014 00:00:00 GMThttp://hdl.handle.net/1957/490012014-05-12T00:00:00ZEffectual template bank for the detection of gravitational waves from inspiralling compact binaries with generic spins
http://hdl.handle.net/1957/48537
Effectual template bank for the detection of gravitational waves from inspiralling compact binaries with generic spins
Ajith, P.; Fotopoulos, N.; Privitera, S.; Neunzert, A.; Mazumder, N.; Weinstein, A. J.
We report the construction of a three-dimensional template bank for the search for gravitational waves
from inspiralling binaries consisting of spinning compact objects. The parameter space consists of two
dimensions describing the mass parameters and one “reduced-spin” parameter, which describes the secular
(nonprecessing) spin effects in the waveform. The template placement is based on an efficient stochastic
algorithm and makes use of the semianalytical computation of a metric in the parameter space. We
demonstrate that for “low-mass” (m₁ + m₂ ≲ 12M[subscript ⊙]) binaries, this template bank achieves effective fitting
factors ∼0.92–0.99 towards signals from generic spinning binaries in the advanced detector era over the
entire parameter space of interest (including binary neutron stars, binary black holes, and black-hole
neutron-star binaries). This provides a powerful and viable method for searching for gravitational waves
from generic spinning low-mass compact binaries. Under the assumption that spin magnitudes of black
holes (neutron stars) are uniformly distributed between 0–0.98 [0–0.4] and spin angles are isotropically
distributed, the expected improvement in the average detection volume (at a fixed signal-to-noise-ratio
threshold) of a search using this reduced-spin bank is ∼20%–52%, as compared to a search using a
nonspinning bank.
This is the publisher’s final pdf. The published article is copyrighted by the American Physical Society and can be found at: http://journals.aps.org/prd/.
Tue, 08 Apr 2014 00:00:00 GMThttp://hdl.handle.net/1957/485372014-04-08T00:00:00Z