CQT Talk by Kenji Toyoda, Osaka University

Title: Phonon-based systems and a quantum rotor in trapped ions for quantum information processing
Date/Time: 26-Apr, 04:00PM
Venue: CQT Level 3 Seminar Room, S15-03-15

Abstract: In the study of quantum information processing using trapped ions, phonons have been usually used as mediators of information, while they have useful properties in their own right for use as independent degrees of freedom. Phonons obey the Bose-Einstein statistics, and can take global as well as local characteristics by tuning trap parameters. These properties can be utilized for such areas as quantum simulation and quantum computation. In this talk I would like to present three topics related to experiments using phonons or motions in trapped ions. The first one is experiments on two-phonon interference and prospects toward realization of phonon-based information processing including boson sampling. The second topic is the quantum simulation of strongly interacting particles in solid-state materials based on polaritonic quasiparticles in trapped ions. Polaritonic quasiparticles, each of which is a superposition of an internal excitation and a phonon, are produced by illuminating red-sideband optical pulses to ions and are considered to be repulsively interacting with each other. The last topic is the study of a ''quantum rotor'' made from a three-ion crystal in a triangular shape. The superpositions of optically discernible two orientations are realized by cooling a rotational mode to its ground state and by applying a static magnetic field.

CQT Outreach by Troy Lee, CQT

Title: What quantum computing cannot do
Date/Time: 15-May, 06:30PM
Venue: Supply & Demande Esplanade - 8 Raffles Avenue, #01-13 Esplanade Mall

Abstract: In the popular press, quantum computers are often portrayed as being able to try all possible solutions to a problem at once. This is not the case, and the reality is much more subtle and interesting. We will see with an example that the real task in devising a quantum algorithm is to use interference (as when two water waves collide) to increase the probability of seeing good solutions and decrease the probability of seeing bad ones. Registration details: https://pintofsciencesg.wixsite.com/2018/atoms-to-galaxies-quantum-computing

Quantum Technologies in Space

Date/Time: 16-May - 16-May
Venue: CQT Level 3 Seminar Room, S15-03-15

The aim of Quantum Technologies in Space workshop is to explore the intersection between space engineering and applicable technologies emerging from atomic and optical physics. Representatives from groups working in related fields are attending to summarise the progress of their experiments and discuss strategies for making them ready for space.

This workshop is organised by the team of Alexander Ling under the collaboration between National University of Singapore and Humboldt University of Berlin, Germany.

CQT Talk by Shuming Cheng, Griffith University

Title: Tradeoffs in Quantum Steering
Date/Time: 26-Apr, 11:00AM
Venue: CQT Level 3 Seminar Room, S15-03-15

Abstract: Quantum steering was introduced by Schrodinger, in response to the famous paradox raised by Einstein, Podolsky, and Rosen (EPR) in 1935. It describes the conditioning effect between two parties, Alice and Bob say, that Bob's system could be remotely prepared into different states by different choices of Alice's measurements when they share a pure bipartite non-product state. In this talk, I will talk about the quantum steering for two-qubit states and beyond qubits. In particular, the following issues are examined: 1) Which states Bob's qubit can be steered to by Alice's qubit (qudit)? 2) What is the connection between this set of steered states and the degree of quantum correlation? 3) Which convex decomposition of Bob's local state can be steered to by Alice's qubit (qudit)? 4) And for a multi-party state, are there restrictions on the degree to which one party can steer the systems of all other parties? I will mainly use the quantum steering ellipsoid to tackle these problems and report monogamy relations of quantum steering ellipsoids for qubits systems and beyond qubits. This talk is largely based on my PhD thesis and relevant references are listed below: [1] Quantum steering ellipsoids (Phys. Rev. Lett. 113, 020402); [2] Monogamy of quantum steering ellipsoids (Phys. Rev. A 94, 042105); [3] Monogamy of EPR-steering ( Phys. Rev. Lett. 118, 010401).

CQT Outreach by Jun Ong, Artist

Title: Talk & reception for visiting artist
Date/Time: 04-May, 04:00PM
Venue: CQT Level 3 Seminar Room, S15-03-15

Abstract: Jun is a Kuala Lumpur-based architect and artist. His interest lies at the intersection of fine arts and applied arts in the context of South East Asia. He is currently obsessed with materiality - coupling low-tech materials with hi-tech application primarily with artificial light. Jun has previously worked at practices in Shanghai, Beijing & KL; most recently at the studio of British designer, Tom Dixon in London and has been featured in Hypebeast, Vice, Ignant & Designboom. He studied architecture at the University of Westminster in London and at the University of Melbourne. CQT is partnering with the ArtScience Museum to support Jun to develop an artwork inspired by quantum computing. The piece will be on display at the museum from October. Attend the talk to hear more from the artist about his work and from the museum team about the forthcoming exhibition - there will be opportunities for CQT members to participate as scientific advisors. There will be a tea reception after.

CQT CS Talk by Sourav Chakraborty, Chennai Mathematical Institute

Title: On the power of conditional sampling: a special case of property testing
Date/Time: 25-Apr, 02:00PM
Venue: CQT Seminar Room, S15-03-15

Abstract: In the modern world of big data and fast computing, it is essential to design super fast algorithms. Often reading the whole data is either too costly or time-consuming and sometimes not feasible. Property testing is a subject that deals with these challenges. It tries to design sub-linear algorithms for testing various properties of inputs. The key lies in the way the data is accessed by the algorithm. One of the central problems in property testing and many other related subjects is testing if a distribution has a certain property - say whether a distribution on a finite set is uniform. The conventional way of accessing the distributions is by drawing samples according to the distributions. Unfortunately, in this setting the number of samples that are necessary for testing properties of distribution (for most natural properties) is polynomial in the size of support of the distribution. Thus when the support is relatively big the algorithms become impractical in real life applications. We define a new way of accessing the distribution using ``conditional-sampling oracle". This oracle can be used to design much faster algorithms for testing properties of distribution and thus makes the algorithm useful in practical scenarios. In fact we can show that any label-invariant property of distribution can be tested using constant number of conditional samples. In a couple of recent ongoing projects, we show that the conditional oracle can be implemented in many real life problems and we have been able to show the usefulness of this model and our algorithms in practical purposes and others areas of research. This model also throws a number of interesting theoretical questions.