USC Physics Seminars

                                   Quantum Information – Condensed Matter – Biophysics

These seminars are scheduled on Fridays at 2:00pm, and the location is SSL 150, unless otherwise noted. Some of the seminars will be held jointly with UCLA and CALTECH.
For more information contact Lorenzo Campos Venuti (condensed matter) or Ben Reichardt (quantum information). Biophysics seminars are held the first Friday of each month and are indicated in blue.
UPC seminar location: Ahmanson Center for Biological Research, ACB 238. UPC location for remote viewing of HSC seminars: To be determined.
HSC seminar location: Herklotz seminar room, Zilkha Neurogenetic Institute HSC.  Location for remote viewing of UPC seminars: Herklotz

September 2, 2pm SSL150
Daniel Ben-Zion (UCSD)

SPT and SET physics from decorated string nets

It has been understood for some time now that quantum entanglement plays a central role in classifying phases of matter. Patterns of long range entanglement can distinguish two phases even when symmetries cannot; this is called topological order. One interesting question is: what possibilities are there in systems with both topological order and a global symmetry? On the other hand, even in the absence of topological order it is occasionally possible to have two phases which preserve all symmetries yet are nonetheless distinct. This phenomena is known as a 'symmetry protected topological' phase. In this talk, I will give a few explicit examples of models both with and without topological order, emphasizing the interplay with global symmetries. These models have the feature that domain walls are decorated with auxiliary degrees of freedom which arrange themselves into particular interesting states.

September 7, 2pm SSC319
Si-Hui Tan (CQT Singapore)

An encryption scheme for malleable quantum data with information-theoretic security

We introduce an approach to homomorphic encryption on quantum data. Homomorphic encryption is a cryptographic scheme that allows evaluations to be performed on ciphertext without giving the evaluator access to the secret encryption key. Random operations from an finite abelian unitary group chosen using an encryption key chosen uniformly at random perform the encryption, and operations that lie within the centralizer of the encryption group perform the computation. Since the latter operations commute with any evaluation in the encryption group by definition, applying the inverse of the encryption decrypts the evaluated state, and the decryption key depends only on the encryption key. We show that the group of operations that can be used for computation is isomorphic to a unitary group of a large dimension. Moreover our scheme is information theoretically secure, that is, given orthogonal inputs to our sceme, the evaluator can only extract some amount of classical information that is exponentially suppressed via the Holevo quantity. For a specific encoding, we show that our scheme is able to hide a constant fraction of bits that can be made arbitrarily close to unity.

October 14, 2pm SSL150
Fariborz Nasertorabi (Bridge Institute/USC)

Structure Biology Center at bridge  enables USC research labs to extend their research into structure biology

Structural biology center (SBC) has been established to enable all biology labs at USC to extend their research into the field of structural Bioloy. Here at Bridge Institute we have executed an unique center that can efficiently help labs to progress into structural biology at a minimal cost and without  any prior knowledge in structural biology.  We at the center will work with labs at USC to solve the structure of their protein of interest alone or in complex with ligands/drugs, DNA, RNA or protein. We can additionally do ligand search for the highest stabilizer of the targeted protein.  
During my talk, I will walk you through how the center is set up and how USC labs can best benefit from the center in their research.

October 21, 2pm SSL150
Gerd Bergmann (USC)

Topological Insulators


October 28, 2pm SSL150
Mohseninia (Sharif University of Technology)


November 18, 2pm SSL150
Fabio Traversa (UCSD)

Practical Realization of Memcomputing Machines with Self-Organizing Logic Gates

Memcomputing is a novel computing paradigm based on (non-von Neumann) architectures that employ interconnected memory cells capable of using the collective state of the network to compute.
The computational power of these machines can be substantially increased if we embed in the network some extra information related to the problem to solve. We call this feature "information overhead’’. By taking advantage of this embedded information we can exponentially reduce the complexity of many problems such as the Non-deterministic Polynomial (NP) ones. In fact, the latter ones can be solved by a memcomputing machine with only polynomial resources (in time, space, energy).
A practical realization of these machines can be obtained by employing “self-organizing logic gates’’, i.e., logic gates that can accept inputs from all terminals, including the conventional output terminals and self-organize to satisfy their logic propositions. I will show how to use these gates to solve specific NP problems with polynomial resources. These novel logic gates and circuits can be realized with available nanotechnology components and are scalable.




Januar 2015 - July 2016

January-August 2015

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