January 13, 2017:
Demon Dynamics: Deterministic Chaos, the Szilard Map, and the Intelligence of Thermodynamic Systems by James P. Crutchfield, University of California at Davis 

February 2, 2017:
Holographic quantum errorcorrecting codes by Fernando Pastawski, Institute for Quantum Information and Matter (IQIM) 

March 23, 2017:
Quantum Physics: A Possible Theory of the World as a Whole by Vlatko Vedral, CQT, NUS 

April 27, 2017:
The applied side of Bell nonlocality by Valerio Scarani, CQT, NUS 

May 18, 2017:
Secure quantum computation by Joe Fitzsimons, CQT, NUS & SUTD 

Jul 27, 2017:
Quantum simulations with strongly interacting photons: Merging condensed matter with quantum optics for quantum technologies by Dimitris Angelakis, CQT, NUS 

August 31, 2017:
What do the data tell us? by Berge Englert, CQT, NUS 

September 7, 2017:
Evolution and Perspective of Planar Waveguide Devices by Katsunari Okamoto, Okamoto Laboratory, Japan 

October 19, 2017:
Thermodynamics of Quantum Devices by Ronnie Kosloff, Hebrew University 

October 26, 2017:
Quantum optics with Rydberg atoms by Wenhui Li, Centre for Quantum Technologies, NUS 

November 02, 2017:
Quantum communication and fundamental quantum physics by Nobuyuki Imoto, Osaka University 

November 23, 2017:
Foundations of Latticebased Cryptography by Divesh Aggarwal, Centre for Quantum Technologies, NUS 
Date: 13 January 2017, 4pm
Venue: CQT Seminar Room, S150315
Speaker: James P. Crutchfield, University of California at Davis
We introduce a deterministic chaotic system—the Szilard Map—that encapsulates the measurement, control, and erasure protocol by which Maxwellian Demons extract work from a heat reservoir. Implementing the Demon's control function in a dynamical embodiment, our construction symmetrizes Demon and thermodynamic system, allowing one to explore their functionality and recover the fundamental tradeoff between the thermodynamic costs of dissipation due to measurement and due to erasure. The map's degree of chaos—captured by the KolmogorovSinai entropy—is the rate of energy extraction from the heat bath. Moreover, an engine's statistical complexity quantifies the minimum necessary system memory for it to function. In this way, dynamical instability in the control protocol plays an essential and constructive role in intelligent thermodynamic systems.
Date: 2 February 2017, 4pm
Venue: CQT Seminar Room, S150315
Speaker: Fernando Pastawski, Institute for Quantum Information and Matter (IQIM)
In this talk, I will explore the recent connection between two profound ideas, quantum error correction and holography. The first, represents the realization that reliable quantum information processing could be achieved from imperfect physical components. The second, is a duality between two physical systems on different spatial dimensions which may be identified leading to the exact same predictions. Notably, only one of the two systems explicit includes gravitational features. Recently, quantum information has emerged as a natural tool to relate these two descriptions. As such, concepts familiar to quantum information scientists such as entanglement, compression and quantum error correction are playing important roles in understanding this duality. Conversely, the holographic duality is proposing a new lens through which to explore aspects of quantum error correction. In this talk, I will introduce some of the properties imposed by holography on corresponding quantum errorcorrecting codes, describe explicit tensor network codes which exhibit some of these properties and explore the implications of holographic predictions from a codetheoretic perspective.
Date: 23 March 2017, 4pm
Venue: CQT Seminar Room, S150315
Speaker: Vlatko Vedral, CQT, NUS
Quantum mechanics is commonly said to be a theory of microscopic things: molecules, atoms, subatomic particles. Most physicists, though, think it applies to everything, no matter what the size. The reason its distinctive features tend to be hidden is not a simple matter of scale. Over the past few years experimentalists have seen quantum effects in a growing number of macroscopic systems. The quintessential quantum effect, entanglement, can even occur in large systems as well as warm ones  including living organisms  even though molecular jiggling might be expected to disrupt entanglement.
I will discuss how techniques from information theory, quantum and statistical physics, can all be combined to elucidate the physics of macroscopic objects. Can it be that part of the macroscopic world is quantum, while the rest is, in some sense, classical? This question is also of fundamental importance to the development of future quantum technologies, whose behavior takes place invariably in the macroscopic nonequilibrium quantum regime.
I will discuss the concept of quantum macroscopicity and argue that it should be quantified in terms of coherence based on a set of conditions that should be satisfied by any measure of macroscopic coherence. I will show that this enables a rigorous justification of a previously proposed measure of macroscopicity based on the quantum Fisher information. This might shed new light on the standard Schrödinger cat type interference experiment that is meant to demonstrate the existence of macroscopic superpositions and entanglement.
Date: 27 April 2017, 4pm
Venue: CQT Seminar Room, S150315
Speaker: Valerio Scarani, CQT, NUS
Since its formulation in 1964, Bell's theorem has been classified under "foundations of physics". Ekert's 1991 attempt to relate it to an applied task, quantum cryptography, was quenched by an approach that relied on a different basis and was allegedly equivalent.
Ekert's intuition was finally vindicated with the discovery of "deviceindependent certification" of quantum devices. In this colloquium, I shall revisit the tortuous history of that discovery and mention some of the subsequent results.
Some references that review this topic:
V. Scarani, Acta Physica Slovaca 62, 347 (2012) [https://arxiv.org/abs/1303.3081]
N. Brunner et al., Rev. Mod. Phys. 86, 419 (2014) [https://arxiv.org/abs/1303.2849]
S. Pironio et al., New J. Phys. 18, 100202 (2016) [http://iopscience.iop.org/13672630/focus/FocusonDeviceIndependentQuantumInformation]
Date: 18 May 2017, 4pm
Venue: CQT Seminar Room, S150315
Speaker: Joe Fitzsimons, CQT, NUS & SUTD
The realisation that conventional information theory and models of computation do not account for the full generality of states and operations described by quantum mechanics has led to the burgeoning field of quantum information processing. By harnessing quantum phenomena it is possible to produce stronger forms of cryptography and more efficient algorithms than could exist in a purely classical world. Computer security lies at the intersection of computation and cryptography, and has become an increasingly important topic in recent years. Since quantum information processing leads to advantages in cryptography and computation separately, it is natural to ask whether it may also enhance computer security. In this talk I will argue that the answer to this question is a resounding “yes”, and discuss recent developments in the field.
Date: 27 Jul 2017, 4pm
Venue: CQT Seminar Room, S150315
Speaker: Dimitris Angelakis, CQT, NUS
Classical computers require enormous computing power and memory to simulate even the most modest quantum systems. That makes it difficult to model, for example, why certain materials are insulators and others are conductors or even superconductors. R. Feynman had grasped this since the 1980s and suggested to use instead another more controllable and perhaps artificial quantum system as a "quantum computer" or specifically in this case a "quantum simulator".
Working examples of quantum simulators today include extremely cold atoms trapped with lasers and magnetic fields and ions in electromagnetic traps. Photons and polaritons in lightmatter systems have also recently emerged as a promising avenue especially for simulating out of equilibrium manybody phenomena in a natural drivendissipative setting.
I will briefly review in nonspecialist terms the main results in this area including the early ideas on realizing Mott insulators, Fractional Hall states and Luttinger liquids with photons [1,2,3]. After that I will present in more detail a recent experiment in manybody localization physics using interacting photons in the latest superconducting quantum chip of Google [4]. A simple method to study the energylevelsand their statistics  of manybody quantum systems as they go through the ergodic to manybody localized (MBL) transition, was proposed and implemented. The formation of a mobility edge of an energy band was observed and its shrinkage with disorder toward the center of the bands was measured, a direct observation of a canonical condensed matter concept perhaps for the first time.
Beyond the applications in understanding fundamental physics, the potential impact of this field in different areas of quantum and nano technology and material science will be touched upon.
References
1. D.G. Angelakis and C. Noh “Manybody physics and quantum simulations with light” Report of Progress in Physics, 80 016401 (2016)
2. "Quantum Simulations with Photons and Polaritons: Merging Quantum Optics with Condensed Matter Physics" edited by D.G. Angelakis, Quantum Science and Technology Series, Springer International Publishing, 2017, ISBN 9783319520230, DOI 10.1007/9783319520254
3. Keil, Noh, Rai, Stutzer, Nolte, Angelakis, A. Szameit "Optical simulation of charge conservation violation and Majorana dynamics", Optica 2, 454 (2015)
4. P. Roushan, C. Neill, J. Tangpanitanon,V.M. Bastidas,, …, D.G. Angelakis, J. Martinis. “Spectral signatures of manybody localization of interacting photons”, under review
Date: 31 August 2017, 4pm
Venue: CQT Seminar Room, S150315
Speaker: Berge Englert, CQT, NUS
We gather information about physical systems by observation. In the realm of quantum physics, the experiments give us probabilistic data with natural statistical fluctuations that cannot be reduced by better instrumentation. What do such data tell us about the quantum system under study? A systematic and reliable answer can be given with the methods of quantum state estimation and quantum parameter estimation. I will report on recent developments.
Date: 7 Sept 2017, 4pm
Venue: CQT Seminar Room, S150315
Speaker: Katsunari Okamoto, Okamoto Laboratory, Japan
The talk will review progress and future prospects of planar waveguide devices. Silicabased PLCs (planar lightwave circuits) and InP PICs (photonic integrated circuits) are widely used in the current WDM and FTTH systems. The success of silica PLCs and InP PICs strongly depends on their well controlled core geometries and refractiveindex uniformities. On the other hand silicon photonics is widely regarded as a promising technology to meet the requirements of rapid bandwidth growth and energyefficient communications while reducing cost per bit. One of the most prominent advantages of photonics interconnection over metallic interconnects is higher bandwidth and signal routing functionality using WDM technology. Expectations on Si photonics and technical challenges for silicon photonics will be described.
Date: 19 October 2017, 4pm
Venue: CQT Seminar Room, S150315
Speaker: Ronnie Kosloff, Hebrew University
Quantum thermodynamics addresses the emergence of thermodynamical laws from quantum mechanics. The viewpoint advocated is based on the intimate connection of quantum thermodynamics with the theory of open quantum systems. Quantum mechanics inserts dynamics into thermodynamics giving a sound foundation to finitetimethermodynamics. The emergence of the 0law Ilaw IIlaw and IIIlaw of thermodynamics from quantum considerations will be presented through examples. I will show that the 3level laser is equivalent to Carnot engine. I will reverse the engine and obtain a quantum refrigerator. Different models of quantum refrigerators and their optimization will be discussed. A heatdriven refrigerator (absorption refrigerator) is compared to a powerdriven refrigerator related to laser cooling. This will lead to a dynamical version of the IIIlaw of thermodynamics limiting the rate of cooling when the absolute zero is approached. The thermodynamically equivalence of quantum engines in the quantum limit of small action will be discussed. I will address the question why we find heat exchangers and flywheels in quantum engines. I will present a molecular model of a heat rectifier and a heat pump in a nonMarkovian and strong coupling regime.
Date: 26 October 2017, 4pm
Venue: CQT Seminar Room, S150315
Speaker: Wenhui Li, Centre for Quantum Technologies, NUS
There have been growing research activities involving Rydberg atoms in different directions of quantum optics, both fundamental and applied. In this talk, I first briefly review a few systems and examples, which exploit the exotic properties of Rydberg atoms for new phenomena and applications. I then discuss some of our experimental efforts, including electromagnetically induced transparency and microwaveoptical conversion using Rydberg atoms.
Date: 02 November 2017, 4pm
Venue: CQT Seminar Room, S150315
Speaker: Nobuyuki Imoto, Osaka University
If a highquality entanglement is shared between two distant parties, there are a lot of innovative things we can do such as deviceindependent QKD, which is in fact initiated by Ekert [1]. For this, faithful quantum communication via a noisy and lossy channel is an important element, which is the main research item of my research group [2]. As we proceed this type of research, we encounter some fundamental research themes. For example, we developed a frequency converter of a single photon that maintains coherence and entanglement [3]. Our frequency converter acts as a beamsplitter in frequency domain, whose conversion efficiency is tunable. Using this frequencydomain beamsplitter, we performed HongOuMandel interference [4], where two differentcolor input photons are converted into two samecolor output photons whose color stochastically becomes either of the original two colors. We also performed MachZehnder interference [5], which, in frequency domain, is more difficult than the HOM interference. The second example of fundamental research themes, other than the frequency converter, is cheatsensitive type communication [6], where we can guess the result of the measurement performed by our partner regardless whether he/she chose from the linear and circular polarization measurements, which at first glance appears to be in conflict with the uncertainty principle. The key is that we not only prepare the initial state of the photon before the partner’s measurement but also measure its final state after the partner’s measurement. This concept is generalized to socalled weak value [7], and we are pursuing the meaning and usage of this new concept [8].
[1] A. K. Ekert, PRL67, 661 (1991).
[2] T. Yamamoto et al., Nature 421, 343346 (2003); Nat. Photon. 2, 488  491 (2008).
[3] R. Ikuta et al., Nat. Commun. 2, 1544 (2011).
[4] T. Kobayashi et al., Nat. Photon. 10, 441–444 (2016).
[5] T. Kobayashi et al., Optics Express, 25, 012052_1_9 (2017).
[6] K. Shimizu et al., PRA84, 022308 (2011).
[7] Y. Aharonov et al., PRL, 60, 1351 (1988).
[8] K. Yokota et al., New J. Phys. 18, 123002 (2016).
Date: 23 November 2017, 4pm
Venue: CQT Seminar Room, S150315
Speaker: Divesh Aggarwal, Centre for Quantum Technologies, NUS
Latticebased cryptosystems are perhaps the most promising candidates for postquantum cryptography as they have strong security proofs based on worstcase hardness of computational lattice problems and are efficient to implement due to their parallelizable structure. Attempts to solve lattice problems by quantum algorithms have been made since Shor’s discovery of the quantum factoring algorithm in the mid1990s, but have so far met with little success if any at all. The main difficulty is that the periodicity finding technique, which is used in Shor’s factoring algorithm and related quantum algorithms, does not seem to be applicable to lattice problems.
In this talk, I will survey some of the main developments in lattice cryptography over the last decade or so. The main focus will be on the Learning With Errors (LWE) and the Short Integer Solution (SIS) problems, their ringbased variants, their provable hardness under the intractability assumptions of lattice problems and their cryptographic applications.