aspuru-list February 2019

aspuru-list@lists.fas.harvard.edu

12 participants
31 discussions

[Aspuru-Guzik Group List] No group meeting Feb 14

by Riley Hickman

Hi all, Since we all met for Delfina García-Pintos' talk earlier today, and that we will be missing some group members on the Toronto side tomorrow, there will be no group meeting on Thursday Feb. 14. We will resume normal group meeting next week with Tony speaking. Best, Riley

5 years, 2 months

[Aspuru-Guzik Group List] TODAY - HQI Special Seminar - Maryam Salehi

by Ploucha, Clare

Harvard Quantum Initiative Special Seminar Wednesday, February 13 3:00 PM Jefferson 250 Maryam Salehi (Rutgers) The art of defect engineering in epitaxially-grown topological insulators and topological quantum effects Topological insulators (TIs) are a class of electronic materials which are predicted to be insulating in the bulk and conducting on the boundary surfaces. Since their discovery, material defects have remained as the major obstacle to achieving bulk-insulating TIs. Particularly, efforts to obtain TI thin films with suppressed bulk defects and dominant surface transport have always led to introduction of additional surface defects, thereby shifting the Fermi level away from the Dirac point and deep into the conduction (valence) band. The high defect densities obscure the topological surface states (TSS) and make it impossible to access the Dirac point which is crucial for probing the physics of TSS and the zeroth Landau level as well as fabricating TI-based devices. In this talk, I will discuss how defects have been affecting the properties of TIs and show how suppressing defects in V-VI TIs through a proper interface engineering led to achieving unprecedented low carrier density TI films which revealed the heretofore inaccessible topological quantum aspects of TIs, such as TSS-originated quantum Hall effect, quantized Faraday and Kerr rotation, finite-size topological phase transition, etc.

5 years, 2 months

[Aspuru-Guzik Group List] ITAMP/B2 Winter Graduate School - March 10-16

by Dakoulas, Samantha R

Dear All: The next ITAMP/B2 Winter Graduate School, scheduled for March 10-16, on the B2 campus in AZ, will be on Quantum Many-Body Systems. There's a stellar list of confirmed lecturers. The student registration will close soon, so if you are interested in attending this school, please do so in the next couple of weeks. The idyllic confines of the B2 campus in the Catalina mountains allow for close encounters between students and lecturers; in the cafeteria, during the lectures, in the wide-open afternoon periods, and in the casitas' common areas. The school web address is: https://www.cfa.harvard.edu/itamp-event/winter-school-2019-quantum-many-bod… 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, 2 months

[Aspuru-Guzik Group List] TODAY - HQI Special Seminar - Loïc Anderegg

by Ploucha, Clare

Harvard Quantum Initiative Special Seminar Tuesday, February 12 3:00 PM Jefferson 250 Loïc Anderegg (Harvard) An Optical Array of Ultracold Molecules and Ultracold Molecular Collisions Over the past decades, ultracold atoms have been brought under exquisite control, opening up many new applications ranging from precision measurements to quantum simulations. In addition to atoms, ultracold molecules, with their rich internal structure, promise to be a powerful quantum resource. This has led to intense efforts in controlling molecules. In this talk, I will report on new methods to cool and trap molecules and the creation of an optical tweezer array of single ultracold molecules. This new platform may be used for exploring many different areas in physics. New features available in molecules, such as long-range dipolar interactions, could be harnessed for molecular qubits, quantum simulation of spin lattice Hamiltonians, studies of ultracold quantum chemistry and precision measurements that probe physics beyond the Standard Model. The methods discussed can be extended beyond diatomic molecules to polyatomics, which have new features advantageous for quantum computation and precision measurement. As an initial demonstration of this versatile tweezer platform, we observe ground electronic, excited rotational state collisions of laser cooled molecules for the first time and measure the corresponding inelastic rate coefficients. -- Clare Ploucha Administrative Program Manager Max Planck/Harvard Research Center for Quantum Optics Department of Physics 17 Oxford Street, Jefferson 357 Cambridge, MA 02138 P: 617-495-3388

5 years, 2 months

[Aspuru-Guzik Group List] Post-doc lunch with Peter Lodahl - Wednesday Nov 28

by Tijs Karman

Dear postdocs, Peter Lodahl is visiting later this week and will be speaking at the joint quantum seminar. This Wednesday (28th) we'll take him to lunch at 12 noon most likely at Russel House (unconfirmed). If you'd like to join, please sign up though the following spreadsheet: https://docs.google.com/spreadsheets/d/163JPLGgsfs3ukrB9p_LzJr7hOc-v6u6n7A9… Best, Tijs Karman

5 years, 2 months

[Aspuru-Guzik Group List] February 15 - HQI Special Seminar - Di Zhu

by Ploucha, Clare

Harvard Quantum Initiative Special Seminar Friday, February 15 3:00 PM Jefferson 250 Di Zhu, MIT Title: Exploiting the microwave properties of superconducting nanowires for advancing single-photon detection The exceptional performance of superconducting nanowire single-photon detectors (SNSPDs), including >90% detection efficiency, picosecond timing resolution, and sub-hertz dark count rate, has recently enabled many impressive demonstrations in quantum science and technology, such as the loophole-free Bell test, and record-distance quantum key distribution. However, many other quantum information processing applications, such as Boson sampling, quantum walk, and linear optical quantum computing, have more demanding requirements on photon detection, such as coincidence counting over hundreds of channels, photon number resolution, and even feed-forward operation. In this talk, we will discuss how exploiting the exotic but long-neglected microwave properties of superconducting nanowires can unlock many of these missing functionalities in SNSPDs. For example, by utilizing the slow speed of light in the nanowires, less than 2% of that in free space, we can construct delay-line-multiplexed detector arrays. From this we have demonstrated a two-terminal array architecture that is suitable for coincidence detection over large numbers of spatial modes in photonic integrated circuits, and capable of resolving photon numbers. We have further demonstrated how impedance matching of the nanowires can achieve “passive amplification” and multi-photon resolution in SNSPDs. Beyond photon detection, the nanowires may be used in diverse applications ranging from microwave coupling and switching to parametric amplification.

5 years, 2 months

[Aspuru-Guzik Group List] [qip] Spring 2019 class

by aram harrow

See below for a course announcement that may be of interest to some on this list. It has been offered before, but not every year. ---------- *MAS.862: The Physics of Information Technology* http://fab.cba.mit.edu/classes/MAS.862/ Thursdays 1:00-4:00 E14-493 Neil Gershenfeld 2019 Have you ever wondered how: - atoms tell time? - antennas form beams? - metamaterials cloak? - noise is generated? - information is measured? - semiconductors switch? - lasers lase? - magnets levitate? - spins are imaged? - quantum states are teleported? - computers can operate reversibly? adiabatically? stochastically? MAS.862 will provide answers to these and many other questions, through a survey of the theoretical foundations and device mechanisms used in information technologies. The schedule will be: 2/07 computation, interactions, units, and magnitudes 2/14 noise in physical systems 2/21 information in physical systems 2/28 electromagnetic fields and waves 3/07 circuits, transmission lines, and waveguides 3/14 antennas 3/21 optics, lensless imaging 3/28 no class (Spring break) 4/04 optical materials and devices 4/11 semiconductor materials and devices 4/18 magnetic materials and devices 4/25 transducers 5/02 measurement and coding 5/09 quantum computing and communications 5/16 development 5/23 presentation These topics will be developed through weekly problem sets, laboratory demonstrations, and analytical, numerical, or experimental semester projects. _______________________________________________ qip mailing list qip(a)mit.edu http://mailman.mit.edu/mailman/listinfo/qip

5 years, 2 months

[Aspuru-Guzik Group List] [qip] EPiQC Monthly Science Talk - Wednesday Feb 13, 2019 1:30PM

by Peter Shor

Hi everybody, We will be joining this talk remotely in the room 6-310 on Wednesday. Peter Prakash Murali Wed 1:30-2:30 PM Feb 13 Title: Noise-Adaptive Compiler Mappings for Noisy Intermediate-Scale Quantum Computers. Prakash Murali, Jonathan M. Baker, Ali Javadi Abhari, Frederic T. Chong and Margaret Martonosi (to appear in ASPLOS'19) Abstract: A massive gap exists between current quantum computing (QC) prototypes, and the size and scale required for many proposed QC algorithms. Current QC implementations are prone to noise and variability which affect their reliability, and yet with less than 80 quantum bits (qubits) total, they are too resource-constrained to implement error correction. The term Noisy Intermediate-Scale Quantum (NISQ) refers to these current and near-term systems of 1000 qubits or less. Given NISQ's severe resource constraints, low reliability, and high variability in physical characteristics such as coherence time or error rates, it is of pressing importance to map computations onto them in ways that use resources efficiently and maximize the likelihood of successful runs. Our work proposes and evaluates backend compiler approaches to map and optimize high-level QC programs to execute with high reliability on NISQ systems with diverse hardware characteristics. Our techniques all start from an LLVM intermediate representation of the quantum program (such as would be generated from high-level QC languages like Scaffold) and generate QC executables runnable on the IBM Q public QC machine. We then use this framework to implement and evaluate several optimal and heuristic mapping methods. These methods vary in how they account for the availability of dynamic machine calibration data, the relative importance of various noise parameters, the different possible routing strategies, and the relative importance of compile-time scalability versus runtime success. Using real-system measurements, we show that fine grained spatial and temporal variations in hardware parameters can be exploited to obtain an average 2.9x (and up to 18x) improvement in program success rate over the industry standard IBM Qiskit compiler. _______________________________________________ qip mailing list qip(a)mit.edu http://mailman.mit.edu/mailman/listinfo/qip

5 years, 2 months

[Aspuru-Guzik Group List] Monday Feb. 11 - Special Seminar - Guido Pagano

by Ploucha, Clare

Special Seminar Monday February 11, 10am. Jefferson 356 Engineering Trapped-Ion Systems for Large Scale Quantum Simulation G. Pagano1 1Joint Quantum Institute and Joint Center for Quantum Information and Computer Science, University of Maryland Department of Physics and National Institute of Standards and Technology, College Park, MD 20742 E-mail: pagano(a)umd.edu<mailto:pagano@umd.edu> 171Yb+ ions can be used as a versatile platform for studying quantum dynamics of strongly correlated many-body quantum systems. In particular I will describe how to realize time-crystalline phases in a Floquet setting, where the spin system exhibits persistent time-correlations under many-body- localized dynamics [1]. I will also present our observation of a new type of out-of- equilibrium dynamical phase transition in a spin system with over 50 spins [2]. Moreover I will show our latest efforts towards scaling up the trapped-ion quantum simulator [3] using a cryo-pumped vacuum chamber where we can trap more than 100 ions indefinitely. The reliable production and lifetime of large linear ion chains enabled us to investigate quasi-particle excitations showing confinement in the post- quench dynamics [4] and the implementation of Quantum Approximate Optimization Algorithms (QAOA) [5]. References: [1] J. Zhang et al., Nature, 543, 217 (2017) [2] J. Zhang, G. Pagano, et al., Nature, 551, 601 (2017) [3] G. Pagano et al., Quantum Sci. Technol., 4, 014004 (2019) [4] F. Liu, et al., arXiv 1810.02365 (2018) [5] G.Pagano, et al., (in preparation 2019)

5 years, 2 months

[Aspuru-Guzik Group List] February 12 - HQI Special Seminar - Loïc Anderegg

by Ploucha, Clare

5 years, 2 months

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aspuru-list February 2019