Upcoming seminars

Adaptive phase estimation with two-mode squeezed-vacuum and parity measurement

Seminar date and time: 
2017-07-19 14:30
Author: 
Zixin Huang
Affiliation: 
The School of Physics; The University of Sydney

A proposed phase-estimation protocol based on measuring the parity of a two-mode squeezed vacuum state at the output of a Mach-Zehnder interferometer shows that the Cramer-Rao sensitivity is sub-Heisenberg [Phys. Rev. Lett. 104, 103602 (2010)]. However, these measurements are problematic, making it unclear if this sensitivity can be obtained with a finite number of measurements. This sensitivity is only for phase near zero, and in this region there is a problem with ambiguity because measurements cannot distinguish the sign of the phase.

Location: 
GiQ's seminar room

Quantum machine learning for quantum anomaly detection

Seminar date and time: 
2017-07-17 15:30
Author: 
Nana Liu
Affiliation: 
Centre for Quantum Technologies, National University of Singapore

Anomaly detection is used for identifying data that does not obey the `normal' data patterns and it nds diverse applications in many important areas like fraud detection, diagnoses, data cleaning and surveillance. With the advent of quantum computing and the future of quantum computing in the cloud and over the quantum internet, anomaly detection will inevitably play an important role in revealing novel or unusual patterns in communicated quantum data. Machine learning algorithms are playing pivotal roles in classical computing, including in anomaly detection.

Location: 
GIQ - Seminar room
Contact: 

Decoding Protocols for Classical Communication on Quantum Channels

Seminar date and time: 
2017-07-17 14:30
Author: 
Matteo Rosati
Affiliation: 
Scuola Normale Superiore and Istituto Nanoscienze-CNR

I discuss the transmission of classical information via quantum carriers with focus on the decoding stage. While the optimal transmission rate and encoding have been well studied in the past providing viable solutions for free-space or optical-fiber communication, a practical decoder is still difficult to design. This is due to the requirement of performing joint measurements over several transmission modes and their difficult implementation with current technology.

Location: 
GIQ - Seminar room
Contact: 

Tensor networks for quantum matter: basics, news and prospects

Seminar date and time: 
2017-06-21 14:30
Author: 
Roman Orus
Affiliation: 

Tensor network states have established themselves as the natural language based on entanglement to describe and numerically simulate quantum many-body systems. In this talk I will first provide a long introduction to what tensor network states are, as well as to some of their related numerical methods. An overall perspective on the field will also be provided. Then, I will review recent progress on this topic conducted in my group.

Location: 
GIQ - Seminar room
Contact: 

Verification of Measurement-Based Quantum Computation

Seminar date and time: 
2017-06-15 14:30
Author: 
Masahito Hayashi

Quantum computation offers a novel way of processing information and promises solution of some classically intractable problems. However, if the component of the quantum computor has some errors, it does not output a correct computation outcome. Since the quantum computor is composed of several components, the unexpected correlation causes unexpected error that cannot be corrected by error correction. To resolve this problem, we need to verify the quantum computor.

Location: 
GIQ - Seminar room

Doped resonating valence bond states: a quantum information study

Seminar date and time: 
2017-06-12 14:30
Author: 
Sudipto Singha Roy
Affiliation: 
HARISH-CHANDRA RESEARCH INSTITUTE, ALLAHABAD, UTTAR PRADESH, INDIA

Abstract:

Resonating valence bond states have played a crucial role in the description of exotic

phases in strongly correlated systems, especially in the realm of Mott insulators and the

associated high­Tc superconducting phase transition. In particular, RVB states are

considered to be an important system to study the ground state properties of the doped

quantum spin­1/2 ladder. It is therefore interesting to understand how quantum correlations

are distributed among the constituents of these composite systems. In this regard, we

Location: 
GiQ's seminar room

Quantum and Information Thermodynamics: A Unifying Framework based on Repeated Interactions

Seminar date and time: 
2017-06-07 14:00
Author: 
Philipp Strasberg
Affiliation: 

In this talk I will show how to expand the standard thermodynamic framework of a system coupled to a thermal reservoir by considering a stream of independently prepared units repeatedly put into contact with the system. These units can be in any nonequilibrium state and interact with the system with an arbitrary strength and duration. We will see that this stream constitutes an effective resource of nonequilibrium free energy and identify the conditions under which it behaves as a heat, work or information reservoir.

Location: 
GIQ - Seminar room
Contact: 

Irreducible noncontextuality inequalities from the Kochen-Specker theorem

Seminar date and time: 
2017-05-31 14:30
Author: 
Ravi Kunjwal
Affiliation: 
Perimeter Institute

Recent work (Kunjwal and Spekkens, Phys. Rev. Lett. 115, 110403 (2015)) has shown how operational noncontextuality inequalities robust to noise can be obtained from Kochen-Specker uncolourable (or KS-uncolourable) hypergraphs without assuming that measurement outcomes are fixed deterministically by the ontic state of the system in an underlying ontological model. This result was obtained by an explicit numerical enumeration of all the extremal points of the polytope of (measurement) noncontextual assignments of probabilities to the KS-uncolourable hypergraph.

Location: 
GIQ seminar room C5/260

A single atom heat engine

Seminar date and time: 
2017-05-30 16:00
Author: 
Eric Lutz
Affiliation: 
University of Erlangen-Nürnberg, Germany

We review the miniaturization of heat engines towards the nanoscale. We

discuss in detail the experimental realization of a single atom engine

using an ultracold trapped ion coupled to engineered reservoirs. We

further address the question of how to enter the quantum regime and

exploit quantum effects to enhance the performance of the machine.

Location: 
GiQ's seminar room
Contact: 

Digital quantum metrology

Seminar date and time: 
2017-05-29 16:00
Author: 
Lorenzo Maccone
Affiliation: 
Universita' di Pavia, Italy

Quantum Metrology calculates the ultimate precision of all estimation

strategies, measuring what is their root mean-square error (RMSE) and

their Fisher information. Here, instead, we ask how many bits of the

parameter we can recover, namely we derive an information-theoretic

quantum metrology. In this setting we redefine "Heisenberg bound" and

"standard quantum limit" (the usual benchmarks in quantum estimation

Location: 
GiQ's seminar room

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