Talks

9133 - 9144 of 18100 Results

Irreversibility and Entanglement Spectrum Statistics in Quantum Circuits

Eduardo Mucciolo University of Central Florida

September 30, 2014

PIRSA:14090028

Condensed Matter
3d Gravity, Universality and Poincare Series

September 30, 2014

PIRSA:14090005
PHYS 781 - Lecture 4

Niayesh Afshordi University of Waterloo

September 30, 2014

PIRSA:14090085
ADMX: The Axion Dark Matter Experiment

Gray Rybka University of Washington

September 30, 2014

PIRSA:14090067

High Energy Physics
From Black Holes to Big Bang, and Back

Niayesh Afshordi University of Waterloo

September 30, 2014

PIRSA:14090088
PHYS 781 - Lecture 3

Niayesh Afshordi University of Waterloo

September 26, 2014

PIRSA:14090087
14/15 PSI Quantum Theory-15

Joseph Emerson Institute for Quantum Computing (IQC)

September 26, 2014

PIRSA:14090060
14/15 PSI - Relativity- Lecture 15

Neil Turok University of Edinburgh

September 26, 2014

PIRSA:14090064
PHYS 781 - Lecture 2

Niayesh Afshordi University of Waterloo

September 25, 2014

PIRSA:14090086
14/15 PSI Quantum Theory-14

Joseph Emerson Institute for Quantum Computing (IQC)

September 25, 2014

PIRSA:14090059
14/15 PSI - Relativity- Lecture 14

Neil Turok University of Edinburgh

September 25, 2014

PIRSA:14090063
Fault-tolerant logical gates in quantum error-correcting codes

Beni Yoshida Perimeter Institute for Theoretical Physics

September 24, 2014

PIRSA:14090032

Quantum Physics

Irreversibility and Entanglement Spectrum Statistics in Quantum Circuits

Eduardo Mucciolo University of Central Florida

September 30, 2014

PIRSA:14090028

Condensed Matter

We show that for a system evolving unitarily under a stochastic quantum circuit, the notions of irreversibility, universality of computation, and entanglement are closely related. As the state of the system evolves from an initial product state, it becomes increasingly entangled until entanglement reaches a maximum. We define irreversibility as the failure to find a circuit that disentangles a maximally entangled state. We show that irreversibility occurs when maximally entangled states are generated with a quantum circuit formed by gates from a universal quantum computation set. We find that irreversibility is also associated to a Wigner-Dyson statistics in the fluctuations of spacings between adjacent eigenvalues of the system’s reduced density matrix. In contrast, when the system is evolved with a non-universal set of gates, the statistics of the entanglement spacing deviates from Wigner-Dyson and the disentangling algorithm succeeds. We discuss how these findings open a new way to characterize non-integrability in quantum systems.
3d Gravity, Universality and Poincare Series

September 30, 2014

PIRSA:14090005

Modular invariance plays an important role in the AdS3/CFT2 correspondence. Using modular invariance, I discuss under what conditions a 2d CFT shows a Hawking-Page phase transition in the large c limit, and what this implies for the range of validity of the Cardy formula and the universality of its spectrum. I will also discuss partition functions obtained by summing over the modular group, how their properties are compatible with their gravity interpretation, and briefly touch on implications for the existence of pure gravity.
PHYS 781 - Lecture 4

Niayesh Afshordi University of Waterloo

September 30, 2014

PIRSA:14090085
ADMX: The Axion Dark Matter Experiment

Gray Rybka University of Washington

September 30, 2014

PIRSA:14090067

High Energy Physics

Axions are an exceptionally well-motivated dark matter candidate in addition to being a consequence of the Peccei-Quinn solution to the strong CP problem. ADMX (Axion Dark Matter eXperiment) has recently been selected as the axion search for the US DOE Second-Generation Dark Matter Program. I will discuss the imminent upgrade of ADMX to a definitive search for micro-eV mass dark matter axions as well as the ongoing research and development of new technologies to expand the reach of ADMX to the entire plausible dark matter axion mass range.
From Black Holes to Big Bang, and Back

Niayesh Afshordi University of Waterloo

September 30, 2014

PIRSA:14090088

By now, both black hole astrophysics and big bang cosmology are empirically well-established disciplines of physics and astronomy. They are also the only circumstances in nature where Einstein's general relativity can be seen in its full glory, and yet contain within them, its eventual and inevitable folly. Here, I will outline subtle lines evidence for why a phenomenologically successful description of big bang cosmology and black hole horizons may be intimately connected. These lines include a holographic description of big bang, thermal tachyacoustic cosmology, and the firewall controversy. Astrophysical observations, ranging from CMB and dark energy probes, to astrophysical neutrinos could shed further light on these potential connections.
PHYS 781 - Lecture 3

Niayesh Afshordi University of Waterloo

September 26, 2014

PIRSA:14090087
14/15 PSI Quantum Theory-15

Joseph Emerson Institute for Quantum Computing (IQC)

September 26, 2014

PIRSA:14090060
14/15 PSI - Relativity- Lecture 15

Neil Turok University of Edinburgh

September 26, 2014

PIRSA:14090064
PHYS 781 - Lecture 2

Niayesh Afshordi University of Waterloo

September 25, 2014

PIRSA:14090086
14/15 PSI Quantum Theory-14

Joseph Emerson Institute for Quantum Computing (IQC)

September 25, 2014

PIRSA:14090059
14/15 PSI - Relativity- Lecture 14

Neil Turok University of Edinburgh

September 25, 2014

PIRSA:14090063
Fault-tolerant logical gates in quantum error-correcting codes

Beni Yoshida Perimeter Institute for Theoretical Physics

September 24, 2014

PIRSA:14090032

Quantum Physics

Recently, Bravyi and Koenig have shown that there is a tradeoff between fault-tolerantly implementable logical gates and geometric locality of stabilizer codes. They consider locality-preserving operations which are implemented by a constant depth geometrically local circuit and are thus fault-tolerant by construction. In particular, they shown that, for local stabilizer codes in D spatial dimensions, locality preserving gates are restricted to a set of unitary gates known as the D-th level of the Clifford hierarchy. In this paper, we elaborate this idea and provide several extensions and applications of their characterization in various directions. First, we present a new no-go theorem for self-correcting quantum memory. Namely, we prove that a three-dimensional stabilizer Hamiltonian with a locality-preserving implementation of a non-Clifford gate cannot have a macroscopic energy barrier. Second, we prove that the code distance of a D-dimensional local stabilizer code with non-trivial locality-preserving m-th level Clifford logical gate is upper bounded by L^{D+1-m}. For codes with non-Clifford gates (m>2), this improves the previous best bound by Bravyi and Terhal. Third we prove that a qubit loss threshold of codes with non-trivial transversal m-th level Clifford logical gate is upper bounded by 1/m. As such, no family of fault-tolerant codes with transversal gates in increasing level of the Clifford hierarchy may exist. This result applies to arbitrary stabilizer and subsystem codes, and is not restricted to geometrically-local codes. Fourth we extend the result of Bravyi and Koenig to subsystem codes. A technical difficulty is that, unlike stabilizer codes, the so-called union lemma does not apply to subsystem codes. This problem is avoided by assuming the presence of error threshold in a subsystem code, and the same conclusion as Bravyi-Koenig is recovered. This is a joint work with Fernando Pastawski. arXiv:1408.1720

Title	Date	Collection	Type	Info
Irreversibility and Entanglement Spectrum Statistics in Quantum Circuits	2014‑09‑30	Quantum Matter	Scientific Series	View details
3d Gravity, Universality and Poincare Series	2014‑09‑30	Quantum Fields and Strings	Scientific Series	View details
PHYS 781 - Lecture 4	2014‑09‑30	PHYS 781 - Fundamentals of Astrophysics	Course	View details
ADMX: The Axion Dark Matter Experiment	2014‑09‑30	Particle Physics	Scientific Series	View details
From Black Holes to Big Bang, and Back	2014‑09‑30	Cosmology and Gravitation	Scientific Series	View details
PHYS 781 - Lecture 3	2014‑09‑26	PHYS 781 - Fundamentals of Astrophysics	Course	View details
14/15 PSI Quantum Theory-15	2014‑09‑26	14/15 PSI - Quantum Theory	Course	View details
14/15 PSI - Relativity- Lecture 15	2014‑09‑26	14/15 PSI -Relativity	Course	View details
PHYS 781 - Lecture 2	2014‑09‑25	PHYS 781 - Fundamentals of Astrophysics	Course	View details
14/15 PSI Quantum Theory-14	2014‑09‑25	14/15 PSI - Quantum Theory	Course	View details
14/15 PSI - Relativity- Lecture 14	2014‑09‑25	14/15 PSI -Relativity	Course	View details
Fault-tolerant logical gates in quantum error-correcting codes	2014‑09‑24	Perimeter Institute Quantum Discussions	Scientific Series	View details

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Format results

Irreversibility and Entanglement Spectrum Statistics in Quantum Circuits

3d Gravity, Universality and Poincare Series

PHYS 781 - Lecture 4

ADMX: The Axion Dark Matter Experiment

From Black Holes to Big Bang, and Back

PHYS 781 - Lecture 3

14/15 PSI Quantum Theory-15

14/15 PSI - Relativity- Lecture 15

PHYS 781 - Lecture 2

14/15 PSI Quantum Theory-14

14/15 PSI - Relativity- Lecture 14

Fault-tolerant logical gates in quantum error-correcting codes

Irreversibility and Entanglement Spectrum Statistics in Quantum Circuits

3d Gravity, Universality and Poincare Series

PHYS 781 - Lecture 4

ADMX: The Axion Dark Matter Experiment

From Black Holes to Big Bang, and Back

PHYS 781 - Lecture 3

14/15 PSI Quantum Theory-15

14/15 PSI - Relativity- Lecture 15

PHYS 781 - Lecture 2

14/15 PSI Quantum Theory-14

14/15 PSI - Relativity- Lecture 14

Fault-tolerant logical gates in quantum error-correcting codes