aspuru-list September 2018

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11 participants
31 discussions

[Aspuru-Guzik Group List] [qip] meeting today at 11am

by Aram Harrow

Dear quanta, This is a reminder that we have a meeting today at 11am in room 6-310. Joel Klassen is visiting and will tell us about stoquastic Hamiltonians. -aram _______________________________________________ qip mailing list qip(a)mit.edu http://mailman.mit.edu/mailman/listinfo/qip

5 years, 6 months

[Aspuru-Guzik Group List] Joint Quantum Sciences Seminar - Wednesday, October 3, 2018 @ 4:00 - Prof. Margaret Reid

by Dakoulas, Samantha R

ITAMP/HQOC Joint Quantum Sciences Seminar Wednesday, October 3, 2018 4:00 PM, Jefferson 250 Prof. Margaret Reid, Swinburne University of Technology “Mesosopic Einstein-Podolsky-Rosen states of massive systems” The demonstration of long-lived entanglement between two separated massive systems opens up the possibility of new tests of quantum mechanics and decoherence theories. For example, the intriguing idea of spatially dependent decoherence was put forward by Furry [1] in response to Einstein-Podolsky-Rosen’s (EPR) paradox paper [2], which highlighted the inconsistency of quantum mechanics with the classical premise of local realism. Furry’s hypothesis is not a part of conventional quantum mechanics. It could occur in a modified quantum mechanics. In the EPR paradox, a measurement made by an observer at one location can seemingly instantaneously affect the quantum state at another. States that demonstrate the correlations of an EPR paradox were thus called “steerable” by Schrodinger. Here, we will present evidence for EPR steerable entangled states of 40,000 atoms generated in a Bose-Einstein condensate [3]. The structure of the correlations can be further analysed, to deduce miniature cat-type paradoxes with atoms. In order to investigate EPR steerable states with spatial separations, we present a protocol for creating, storing and retrieving EPR steerable states of an opto-mechanical oscillator [4]. This leads us to consider the possibility of generating mechanical Schrodinger cat-states, and to test macroscopic realism for massive systems using Leggett–Garg and Bell inequalities in time. [1] W. H. Furry, Phys. Rev. 49, 393 (1936). [2] A. Einstein, B. Podolsky, and N. Rosen, Phys. Rev. 47, 777 (1935). [3] M. Egorov et. al, Phys. Rev. A 84, 021605 (2011). [4] S. Kiesewetter, R. Y. Teh, P. Drummond and M. Reid, Phys. Rev. Lett. 119, 023601 (2017). [5] S. Coleman, Phys. Rev. D 15, 2929 (1977). [6] O. Fialko et. al., J. Phys. B 50 024003 (2017). Refreshments provided at 4:00 pm. Samantha Dakoulas Faculty Assistant to Professors Lukin & Greiner & their groups Department of Physics 17 Oxford St., Lyman 324A Cambridge, MA 02138 P. (617) 496-2544

5 years, 7 months

[Aspuru-Guzik Group List] Group meeting, Thu 2:30 PM, Div Room

by Ian Kivlichan

Hi all, Tomorrow David will speak at group meeting at 2:30. See below for his title and abstract. Also, please keep in mind this (Thursdays 2:30) will be the group meeting time at least for the rest of the semester. All the best, Ian ----------------- Title: Could heating stabilize a system? Abstract: Our basic intuition tells us that an increase on a system temperature tends to destabilize it. The physical mechanism behind this effect is related to an increase of thermal fluctuations that allow the system to cross potential barriers. This notion is true for systems on thermal equilibrium. Nevertheless, if a system is out of equilibrium a temperature rise may actually stabilize it. In this talk I will explain this counterintuitive effect in a particular system: molecular junctions.

5 years, 7 months

[Aspuru-Guzik Group List] Competition for name of instiitute

by Alan Aspuru-Guzik

Dear group, Your mission, if you choose to accept it, is to come up with an impactful and memorable name for our Consortium on materials acceleration platforms (MAPs). What is the Consortium about? The goal of our Consortium is to develop MAPs like Ada that fully integrate automated robotics with rapid characterization and AI. We will foster strategic, multidisciplinary partnerships between academia, government, and the private sector to catalyze disruptive innovation in the area of materials discovery. How do I enter the contest? Follow this link <https://docs.google.com/forms/d/e/1FAIpQLSfy7K_yFn6X1NLyeOaY6bA3FL2b79PwjOq…> (up to 5 entries per person) How will a winner be decided? The founding members of the Consortium (Berlinguette, Trbukait, Hein, and Aspuru-Guzik) will confer with an advisory panel to select a champion name. What is the submission deadline? Submissions will close on Friday the 28th of September at 12:00 pm P.T. What if I win? A $100 Amazon giftcard is up for grabs! Imagine the possibilities… Any other inspiration? Keywords to consider: materials acceleration, global innovation, discovery, advanced materials Past iterations and suggestions: Materials Acceleration & Global Innovation Consortium (MAGIC) International Materials Acceleration Global Institute (iMAGI) Innovation on Materials Accelerated Discovery Consortium (IMAD) *Note: the name does not have to be an acronym! Good luck, and may the best name win! -- Alán Aspuru-Guzik Professor of Chemistry and Computer Science | Vector Institute Canada 150 Research Chair in Quantum Chemistry | CIFAR Senior Fellow University of Toronto | 80 St George St | Toronto, ON M5S 3H6, Canada http://matter.toronto.edu Twitter @A_Aspuru_Guzik aspuru(a)utoronto.ca

5 years, 7 months

[Aspuru-Guzik Group List] [qip] visit and talks by Joel Klassen and Urmila Mahadev

by Aram Harrow

Dear quanta, Joel Klassen is visiting from now through Oct 5, and will speak this Friday at the group meeting. Urmila Mahadev is visiting from Oct 23-26 and is giving two talks in the CS department. Joel's talk this Friday: Title: When is a Hamiltonian Stoquastic? Abstract: I will discuss a class of Hamiltonians called stoquastic Hamiltonians. Systems with Hamiltonians of this form avoid the sign problem and thus typically lend themselves well to quantum Monte Carlo methods. Understanding when a Hamiltonian is stoquastic is a non-trivial task, since the property is only manifest in a correctly chosen basis. Here I review work done, in collaboration with Barbara Terhal, to construct algorithms for deciding when a Hamiltonian is stoquastic, and for producing the correct choice of basis. Urmila's first talk is the ToC colloquium (4pm , Oct 23, 32-G449) https://toc.csail.mit.edu/node/1254 Classical verification of quantam computation Abstract: We present the first protocol allowing a classical computer to interactively verify the result of an efficient quantum computation. We achieve this by constructing a measurement protocol, which enables a classical verifier to use a quantum prover as a trusted measurement device. The protocol forces the prover to behave as follows: the prover must construct an n qubit state of his choice, measure each qubit in the Hadamard or standard basis as directed by the verifier, and report the measurement results to the verifier. The soundness of this protocol is enforced based on the assumption that the learning with errors problem is computationally intractable for efficient quantum machines. Her second talk is in the crypto seminar series (10:30-12pm, Oct 26, 32-G882) https://toc.csail.mit.edu/node/1253 Classical homomorphic encryption for quantum circuits Abstract: We present the first leveled fully homomorphic encryption scheme for quantum circuits with classical keys. The scheme allows a classical client to blindly delegate a quantum computation to a quantum server: an honest server is able to run the computation while a malicious server is unable to learn any information about the computation. We show that it is possible to construct such a scheme directly from a quantum secure classical homomorphic encryption scheme with certain properties. Finally, we show that a classical homomorphic encryption scheme with the required properties can be constructed from the learning with errors problem. _______________________________________________ qip mailing list qip(a)mit.edu http://mailman.mit.edu/mailman/listinfo/qip

5 years, 7 months

[Aspuru-Guzik Group List] ITAMP Lunch Seminar - Florentin Reiter, Harvard (September 27th)

by Zolfaghari Jooya, Hossein

*ITAMP Lunch Seminar* *Speaker: * Florentin Reiter (Harvard) *Date:* Thursday, September 27th *Time:* 12:00-1:00 pm Includes Pizza. *Title:* *Cooperative Breakdown of the Oscillator Blockade in the Dicke Model* *Abstract: *The Dicke model [1] describes the coupling of an ensemble of spins to a harmonic oscillator. Its superradiant phase transition [2] constitutes a prime example of a non-equilibrium phase transition, which can be observed experimentally [3]. We demonstrate that, in addition, a dissipative Dicke model can undergo a second phase transition to a non-stationary phase, characterized by unlimited heating of the harmonic oscillator. Identifying the mechanism of the phase transition, we conclude that the novel phase transition can be understood as a cooperative breakdown of the oscillator blockade [4] which otherwise prevents higher excitation of the system. We discuss the relationship to previously observed breakdown phenomena [5] and derive the scaling of the critical coupling with the system size. The model can be realized using standard experimental platforms such as trapped ions. [1] R. H. Dicke, Phys. Rev. 93, 99 (1954). [2] K. Hepp and E. H. Lieb, Ann. Phys. 76, 360 (1973); Y. K. Wang and F. T. Hioe, Phys. Rev. A 7, 831 (1973). [3] K. Baumann et al., Nature 464, 1301 (2010); Z. Zhiqiang et al., Optica 4, 424 (2017). [4] F. Reiter, T. L. Nguyen, J. P. Home, and S. F. Yelin, arxiv:1807.06026 (2018). [5] H. J. Carmichael, Phys. Rev. X 5, 031028 (2015); J. Fink et al., Phys. Rev. X 7, 011012 (2017). *Location: *B-106 @ Center for Astrophysics (60 Garden Street <https://maps.google.com/?q=60+Garden+Street&entry=gmail&source=g>) *Directions: *After entering the lobby of the CfA, turn right to enter the hallway of the B building. In the hallway, turn right again, B-106 will be at the end of the hallway on the left side.

5 years, 7 months

[Aspuru-Guzik Group List] Joint Quantum Sciences Seminar - Wednesday, September 26, 2018 @ 4:00 - Profs. Peter Drummond & Margaret Reid

by Dakoulas, Samantha R

ITAMP/HQOC Joint Quantum Sciences Seminar Wednesday, September 26, 2018 4:00 PM, Jefferson 250 Prof. Margaret Reid, Swinburne University of Technology “Mesosopic Einstein-Podolsky-Rosen states of massive systems” The demonstration of long-lived entanglement between two separated massive systems opens up the possibility of new tests of quantum mechanics and decoherence theories. For example, the intriguing idea of spatially dependent decoherence was put forward by Furry [1] in response to Einstein-Podolsky-Rosen’s (EPR) paradox paper [2], which highlighted the inconsistency of quantum mechanics with the classical premise of local realism. Furry’s hypothesis is not a part of conventional quantum mechanics. It could occur in a modified quantum mechanics. In the EPR paradox, a measurement made by an observer at one location can seemingly instantaneously affect the quantum state at another. States that demonstrate the correlations of an EPR paradox were thus called “steerable” by Schrodinger. Here, we will present evidence for EPR steerable entangled states of 40,000 atoms generated in a Bose-Einstein condensate [3]. The structure of the correlations can be further analysed, to deduce miniature cat-type paradoxes with atoms. In order to investigate EPR steerable states with spatial separations, we present a protocol for creating, storing and retrieving EPR steerable states of an opto-mechanical oscillator [4]. This leads us to consider the possibility of generating mechanical Schrodinger cat-states, and to test macroscopic realism for massive systems using Leggett–Garg and Bell inequalities in time. Prof. Peter D Drummond, Swinburne University of Technology “Simulations of many-body systems: Furry and Coleman revisited” Wendell Furry [1] and Sydney Coleman [5] were two of Harvard's most original quantum theorists. What can modern technology contribute to their work? Experimentally tested simulations of optomechanics[4] and atom interferometers [3], with thermal noise and losses, will be used to analyse proposals for testing Furry's nonlocal decoherence, and Coleman's QFT tunnelling to the true vacuum. Both entanglement decoherence and massive Schrodinger cats are testable [4] through an optomechanical memory, simulated using the positive-P representation. Coleman's vacuum tunneling idea will be applied to construct a proposal for a laboratory model of the quantum fluctuations in the 'Big Bang', using a coupled BEC experiment simulated with a Wigner representation [6]. [1] W. H. Furry, Phys. Rev. 49, 393 (1936). [2] A. Einstein, B. Podolsky, and N. Rosen, Phys. Rev. 47, 777 (1935). [3] M. Egorov et. al, Phys. Rev. A 84, 021605 (2011). [4] S. Kiesewetter, R. Y. Teh, P. Drummond and M. Reid, Phys. Rev. Lett. 119, 023601 (2017). [5] S. Coleman, Phys. Rev. D 15, 2929 (1977). [6] O. Fialko et. al., J. Phys. B 50 024003 (2017). Refreshments provided at 4:00 pm. Samantha Dakoulas Faculty Assistant to Professors Lukin & Greiner & their groups Department of Physics 17 Oxford St., Lyman 324A Cambridge, MA 02138 P. (617) 496-2544

5 years, 7 months

[Aspuru-Guzik Group List] [qip] Fwd: [OQE] Special OQE Seminar: Dr. Masoud Mohseni, TODAY, September 21, 2018 at 11:00 AM in the Haus Room, 36-428

by Aram Harrow

This talk is occurring in an hour. ---------- Forwarded message --------- From: Janice L Balzer <balzer(a)mit.edu> Date: Fri, Sep 21, 2018 at 9:12 AM Subject: [OQE] Special OQE Seminar: Dr. Masoud Mohseni, TODAY, September 21, 2018 at 11:00 AM in the Haus Room, 36-428 To: oqe <oqe(a)mit.edu> Special OQE Seminar *TODAY*, September 21, 2018 11:00 AM Haus Room, 36-428 Masoud Mohseni Google Quantum AI Laboratory Title: Quantum-assisted optimization and machine learning on NISQ devices Abstract: We present an overview of our progress on quantum optimization and machine learning at Quantum AI Lab at Google. In particular, we present an end-to-end quantum-assisted optimization engine on Google Cloud Platform. Our physics-inspired approaches use an interplay of thermal and quantum fluctuations to sample from unaccessible low-energy states of spin-glass systems that encode certain hard combinatorial optimization and probabilistic inference problems. We introduce structured droplet instances and show that our hybrid quantum-classical heuristic algorithms can improve over classical techniques, such parallel tempering, that rely on local updates. We also introduce universal discriminative quantum neural networks for classification and purification of quantum data. We train near-term small-scale quantum circuits to classify data represented by non-orthogonal quantum probability distributions using stochastic optimization techniques. This is achieved by iterative interactions of a classical processor with a quantum device to discover the parameters of an unknown non-unitary quantum map which can be implemented via a shallow quantum circuit. Similar small-scale quantum circuit learning could be used for verifying the quantum outputs of other shallow circuits, constructing structured receivers in quantum imaging/sensing, and designing quantum repeaters in quantum communication networks. Bio: Masoud Mohseni is a Senior Research Scientist at Google Quantum Artificial Intelligence Laboratory, where he develops novel quantum optimization and machine learning algorithms. A former research scientist and a principal investigator at the Research Laboratory of Electronics at MIT, Dr. Mohseni has been a scientific consultant at leading industry initiatives on unconventional computing. He obtained his Ph.D in physics in 2007 from University of Toronto. He then moved to Harvard University to complete a postdoctoral program in quantum simulation. Dr. Mohseni’s current research addresses some of the fundamental problems at the interface of artificial intelligence, quantum computing, and physics of complex systems. He has also made seminal contributions to the theory of coherent energy transfer in biological systems. He is an author and the leading editor of the first scientific book on Quantum Effects in Biology that has been published by Cambridge University Press. For a full listing of this semester’s colloquia or to subscribe to the mailing list, please visit www.rle.mit.edu/oqesem _______________________________________________ OQE mailing list OQE(a)mit.edu http://mailman.mit.edu/mailman/listinfo/oqe _______________________________________________ qip mailing list qip(a)mit.edu http://mailman.mit.edu/mailman/listinfo/qip

5 years, 7 months

[Aspuru-Guzik Group List] Special ITAMP lunch seminar - Adi Pick, Technion (September 25th)

by Zolfaghari Jooya, Hossein

*Special ITAMP Lunch Seminar* *Speaker: * Adi Pick (Technion) *Date:* Tuesday, September 25th *Time:* 12:00-1:00 pm Includes Pizza. *Title:* *Applications of exceptional points in photonic, atomic, and solid-state system* *Abstract: *Exceptional points (EPs) are exotic degeneracies in non-Hermitian systems. Due to their counterintuitive properties and recent realizations, EPs have been the focus of immense attention. In this talk, I will present three new applications of EPs: (I) Enhancing spontaneous emission (SE) near EPs [1-3], (II) controlling atomic and molecular absorption [4], and (III) creating topological mode switches using open quantum systems. I will begin by presenting our formula for the SE spectrum near EPs, where standard mode-expansion methods lead to erroneous and divergent results. I will further show that significant SE enhancements can occur in systems with gain (exceeding 400×). In the second part of the talk, I will present a method for optically inducing EPs in atomic systems, and show that slight changes in the laser parameters may lead to either dramatic enhancement or to complete inhibition of the absorption. Finally, I will describe the intriguing properties of topological mode switches in open quantum systems. When varying a system slowly along a closed path, an adiabatic system returns to its initial state - unless the path encircles an isolated EP, in which case the initial and final states switch. However, non-Hermitian systems do not always evolve adiabatically, and the outcome of the switch depends on the chirality of the path. We explore asymmetric mode switching in open quantum systems, which offer a rich EP structure, including high-order isolated and embedded EPs. [1] A Pick, B Zhen, OD Miller, CW Hsu, AW Rodriguez, M Soljacic, and SG Johnson, “General theory of spontaneous emission near exceptional points,” *Opt. Express.** 25*, 12325 (2017) [2] Z Lin, A Pick, M Loncar, and AW Rodriguez, Inverse design of third-order Dirac exceptional points in photonic crystals. *Phys. Rev. Lett. **117*, 107402 (2017) [3] A Pick, Z Lin, and, AW Rodriguez, “Enhanced nonlinear frequency conversion and Purcell enhancement at exceptional points,” *Phys. Rev. B* *96*, 224303 (2017) [4] A Pick, PR Kapralova-Zdanska, and N Moiseyev, “Optical absorption in atoms and molecules near laser-induced exceptional points,” *arXiv:* 1809.02868 (2018) *Location: *B-106 @ Center for Astrophysics (60 Garden Street <https://maps.google.com/?q=60+Garden+Street&entry=gmail&source=g>) *Directions: *After entering the lobby of the CfA, turn right to enter the hallway of the B building. In the hallway, turn right again, B-106 will be at the end of the hallway on the left side.

5 years, 7 months

[Aspuru-Guzik Group List] No group meeting today + time change to 2:30 PM

by Ian Kivlichan

Hi all, Just a heads up that there will be no group meeting today. We'll resume next week at *2:30 PM* - group meetings will be at that time slot for the indefinite future. All the best, Ian

5 years, 7 months

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aspuru-list September 2018