aspuru-list November 2018

aspuru-list@lists.fas.harvard.edu

8 participants
20 discussions

[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] [qip] QIP seminar, Nov 30, Shruti Puri

by Aram Harrow

Shruti Puri (Yale) QIP Seminar @ MIT, 30-Nov-2018 1:30PM, 6C-402 Title: Quantum Error Correction with Biased Noise Cat-Qubits Abstract Many physical systems exhibit error channels that are strongly biased, that is, one type of error dominates the channel. Naively, in this case error correction becomes much easier and more hardware efficient. However, maintaining the bias while performing gates which do not commute with the dominant error is not possible with two-dimensional systems. In this talk, I will demonstrate a way to circumvent this using the non-trivial topology of a continuous family of Schrödinger cat-state qubits. These bosonic qubits can be experimentally realized in a driven non-linear (Kerr) oscillator and exhibit a phase-flip rate that is exponentially suppressed relative to the bit-flip rate. The phase of the drive provides a continuous parameter that permits topologically-protected realization of CNOT gates in a bias-preserving manner. I will present all the bias-preserving operations possible with these cat qubits and discuss how these can lead to efficient quantum error correction codes. _______________________________________________ qip mailing list qip(a)mit.edu http://mailman.mit.edu/mailman/listinfo/qip

5 years, 4 months

[Aspuru-Guzik Group List] EE Seminar on Friday, November 30th - James Clarke

by Dakoulas, Samantha R

[hseas-logo] Harvard John A. Paulson School of Engineering and Applied Sciences Electrical Engineering Seminar Series James Clarke Intel Corporation “Towards a Large Scale Quantum Computer using Advanced Fabrication Technologies” Friday, November 30, 2018 3:00 – 4:00 p.m. Maxwell Dworkin G125 Light refreshments Today’s quantum processors are limited to 10’s of entangled quantum bits. If you believe the hype, a commercially relevant system is just around the corner that can outperform our largest supercomputers. The reality, however, is that we are at mile 1 of a marathon. There are many unanswered fundamental questions. At Intel, our approach is to rely on the continued evolution of Moore’s Law to build qubit arrays with a high degree of process control. Here, we present progress toward the realization of 300mm Si-MOS based spin qubit devices in a production environment. This includes (i) isotopically purified28Si epi substrates with a compelling LT Hall mobility of ~ 10,000 cm2/Vs, (ii) design of a custom qubit layout, (iii) integration of fin-based spin qubit devices using immersion lithography, moving from classical transistor structures to full spin qubits, and (iv) the realization of quantum dots in a nested gate design novel to a 300mm process line. In addition, this talk will focus on two bottlenecks to moving beyond today’s few-qubit devices. The first bottleneck is in the interconnect design of the quantum circuit. Today’s qubits have personalities. Individual control of each qubit is required. A small quantum processor today has multiple RF and DC wires per qubit. This is a brute force approach to wiring and will not scale to the millions of qubits needed for large applications. The second bottleneck relates to the speed of information turns in quantum development. Fabrication of spin qubits in a silicon substrate bares similarity to conventional transistors from advanced CMOS technologies. One of the above 300mm wafers has over 10,000 individual quantum test structures. Naturally, R&D should be accelerated by the potential volume of statistical data. While automated electrical testing of a CMOS transistor wafer can be completed in less than an hour at room temperature, data collection at cryogenic temperatures is currently limited to a small number of devices with a turnaround of hours to days. Rhetorically speaking, “How can we deliver an exponentially fast compute technology with slow and serial characterization of quantum chips?” Speaker: Jim Clarke is the director of the Quantum Hardware research group within Intel’s Components Research Organization. Jim launched Intel’s Quantum Computing effort in 2015, as well as a research partnership with QuTech (TU Delft and TNO). His group’s primary focus is to use Intel’s process expertise to develop scalable qubit arrays. Prior to his current role, Jim managed a group focused on interconnect research at advanced technology nodes as well as evaluating new materials and paradigms for interconnect performance. He has co-authored more than 70 papers and has several patents. Prior to joining Intel in 2001, Jim completed a B.S. in chemistry at Indiana University, a Ph.D. in physical chemistry at Harvard University and a post-doctoral fellowship in physical organic chemistry at ETH, Zürich. Host: Marko Loncar

5 years, 4 months

[Aspuru-Guzik Group List] Group meeting, Thu Nov 29, 2:30 PM

by Ian Kivlichan

Hi all, Hannah will speak at group meeting tomorrow - see below for her title and abstract. The Div Room's booked until 2:30 for a faculty meeting, so it might be easier for Harvard people to Skype in from New Siberia. All the best, Ian ----------------- Title: Characterization of Training Circuits for Hybrid Quantum-Classical Algorithms Abstract: Performing useful computations with current and near-term quantum computers is becoming increasingly viable due to rapid advances in both algorithms and hardware. A class of algorithms that are promising candidates for demonstrating the utility of near-term quantum computers is the so called hybrid quantum-classical (HQC) algorithms. A common ingredient that plays a crucial role in the algorithmic performance of many HQC algorithms is the parametrized quantum circuit that is tuned to prepare quantum states relevant for (approximately) solving the problem of interest. Despite the importance of these circuits, they are often generated in the absence of a robust theoretical framework. In this work, we introduce several descriptors to characterize a set of parametrized circuits, including a measure of a circuit’s expressibility and how it correlates with algorithmic performance. Ultimately, having a deeper understanding of the qualities associated with an effective parametrized circuit can lead to significant improvements in the overall development of HQC algorithms.

5 years, 4 months

[Aspuru-Guzik Group List] [qip] Fwd: [Theory-seminars] TALK: Tuesday 11-27-2018 Avishay Tal: Oracle Separation of BQP and the Polynomial Hierarchy

by Aram Harrow

This talk is today at 4pm. The main technical heavy lifting is classical but it solves a long-standing problem in quantum complexity theory. ---------- Forwarded message --------- From: <calendar(a)csail.mit.edu> Date: Tue, Nov 27, 2018 at 12:01 AM Subject: [Theory-seminars] TALK: Tuesday 11-27-2018 Avishay Tal: Oracle Separation of BQP and the Polynomial Hierarchy To: <seminars(a)csail.mit.edu>, <theory-seminars(a)csail.mit.edu> Avishay Tal: Oracle Separation of BQP and the Polynomial Hierarchy *Seminar Series:* Theory of Computation (TOC) 2018 *Speaker:* Avishay Tal, Simons Instititue & Stanford University *Host:* Virginia Vassilevska Williams *Date:* Tuesday, November 27, 2018 *Time:* 4:00 PM to 5:00 PM *Location:* Patil/Kiva G449 Abstract: In their seminal paper, Bennett, Bernstein, Brassard and Vazirani [SICOMP, 1997] showed that relative to an oracle, quantum algorithms are unable to solve NP-complete problems in sub-exponential time (i.e., that Grover's search is optimal in this setting). In this work, we show a strong converse to their result. Namely, we show that, relative to an oracle, there exist computational tasks that can be solved efficiently by a quantum algorithm, but require exponential time for any algorithm in the polynomial hierarchy. (The polynomial hierarchy is a hierarchy of complexity classes that captures P, NP, coNP, and their generalizations.) The tasks that exhibit this "quantum advantage" arise from a pseudo-randomness approach initiated by Aaronson [STOC, 2010]. Our core technical result is constructing a distribution over Boolean strings that "look random" to constant-depth circuits of quasi-polynomial size, but can be distinguished from the uniform distribution by very efficient quantum algorithms. Joint work with Ran Raz. For more information please contact: Deborah Goodwin, 617.324.7303, dlehto(a)csail.mit.edu _______________________________________________ Theory-seminars mailing list Theory-seminars(a)lists.csail.mit.edu https://lists.csail.mit.edu/mailman/listinfo/theory-seminars _______________________________________________ qip mailing list qip(a)mit.edu http://mailman.mit.edu/mailman/listinfo/qip

5 years, 4 months

[Aspuru-Guzik Group List] Joint Quantum Seminar - Wednesday, November 28th, 2018 @ 4:00 - Prof. Peter Lodahl

by Dakoulas, Samantha R

Joint Quantum Seminar Wednesday, November 28th, 2018 4:00 PM, Jefferson 250 Prof. Peter Lodahl, Center for Hybrid Quantum Networks (Hy-Q), Niels Bohr Institute “Quantum-Information Processing with Solid-State Single-Photon Emitters”” Semiconductor quantum dots have improved their optical performance dramatically in recent years, and today a clear pathway is laid out for constructing a deterministic and coherent photon-emitter interface by embedding quantum dots in photonic nanostructures [1]. Such an interface can be employed as an on-demand single-photon source for quantum-information applications, but more generally enables single-photon nonlinearities and deterministic quantum gates [2]. We will review the recent experimental progress on quantum dots coupled to nanophotonic waveguides and cavities as a mean to engineer light-matter interaction. We discuss current status on efficiency, coherence[3,4] and brightness [5], as well as the fundamental limits of photon indistinguishability [6,7]. Various potential quantum-information processing protocols are put forward that exploits the deterministic photon-emitter interface for single-photon nonlinear optics and spin physics. Finally, the experimental demonstration of a photonic switched controlled by a single spin coupled to a waveguide is discussed [8]. References: [1] Lodahl et al., Rev. Mod. Phys. 87, 347 (2015). [2] Lodahl, Quantum Science and Technology 3, 013001 (2018). [3] Kirsanske et al., Phys. Rev. B 96, 165306 (2017). [4] Thyrrestrup et al., Nano Letters 18, 1801 (2018) [5] Daveau et al., Optica 4, 178 (2017). [6] Tighineanu et al., Phys. Rev. Lett. 120, 257401 (2018). [7] Dreessen et al., Quantum Science and Technology 4, 015003 (2019). [8] Javadi et al., Nature Nanotechnology 13, 398 (2018). Student Presentation by Tijs Karman will begin at 4:00 Guest Presentation will begin at 4:30 PM Refreshments will be provided 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, 4 months

[Aspuru-Guzik Group List] Fwd: Quantum Computing Event

by Alan Aspuru-Guzik

FYI 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 <https://mailtrack.io/trace/link/9c7dc6c1dc58ef059f3e834268f27e294563ac19?ur…> Twitter @A_Aspuru_Guzik aspuru(a)utoronto.ca ---------- Forwarded message --------- From: Francois Pitt, CS Undergraduate Chair <ugchair(a)cs.utoronto.ca> Date: Fri, Nov 23, 2018 at 8:30 AM Subject: Fwd: Quantum Computing Event To: DCS Faculty <faculty(a)cs.toronto.edu> Cc: <V.Sladojevic-Sola(a)rotman.utoronto.ca> Rotman is hosting a half-day event on Quantum Computing (including a presentation by Alán Aspuru-Guzik) and they have a small number of complimentary tickets available on a first-come, first-served basis — Ravin and I are both uncertain whether we can make it, so these are up for grabs! If you are interested, please reply to this message (set to go to directly to Valeria Sladojevic-Sola at Rotman). Cheers, Francois -------- Forwarded Message -------- Ravin and Francois I wanted to extend an invitation to members of the Computer Science department for an event we are hosting at Rotman on Quantum Computing as part of Rotman’s Speaker Series hosted by TD Management Data and Analytics Lab. We do have some complementary seats through the lab so if either of you or perhaps some interested colleagues/PhDs would like to attend – please let Valeria (cc’d) know and we will register you. I hope to see you both there. http://www.rotman.utoronto.ca/ProfessionalDevelopment/Events/UpcomingEvents… <https://mailtrack.io/trace/link/6438e10dfc7a06585b64c738b658ba478b0015d2?ur…> Kind regards, Susan [image: cid:image001.png@01D3C039.14B436A0] *Susan Christoffersen* William A. Downe BMO Chair in Finance Vice Dean, Undergraduate and Specialized Programs Professor of Finance *t.* 416 946 5647 Room 323 Rotman School of Management 105 St. George Street, Toronto, Canada M5S 3E6 *www.rotman.utoronto.ca <https://mailtrack.io/trace/link/f8b2c54d1570d53d7320ecc47934de36431f6d1e?ur…>* [image: cid:image002.png@01D3C039.14B436A0]

5 years, 4 months

[Aspuru-Guzik Group List] No group meeting tomorrow

by Ian Kivlichan

Hi all, There will be no group meeting tomorrow (due to a conflicting meeting / American Thanksgiving). See you next week, and enjoy the turkey etc! All the best, Ian

5 years, 4 months

[Aspuru-Guzik Group List] [qip] Scott Aaronson talk, Tues Nov 20, 4pm

by Aram Harrow

TOC Seminar - 11/20 - 32G-449 Title: Gentle Measurement of Quantum States and Differential Privacy Abstract: We prove a surprising connection between gentle measurement (where one wants to measure n quantum states, in a way that damages the states only by a little) and differential privacy (where one wants to query a database about n users, in a way that reveals only a little about any individual user). The connection is bidirectional, though with loss of parameters in going from DP to gentle measurement. By exploiting this connection, together with the Private Multiplicative Weights algorithm of Hardt and Rothblum, we're able to give a new protocol for so-called "shadow tomography" of quantum states, which improves over the parameters of a previous protocol for that task due to Aaronson, and which has the additional advantage of being "online" (that is, the measurements are processed one at a time). Joint work with Guy Rothblum (Weizmann Institute); paper still in preparation. _______________________________________________ qip mailing list qip(a)mit.edu http://mailman.mit.edu/mailman/listinfo/qip

5 years, 5 months

[Aspuru-Guzik Group List] [qip] upcoming meetings and talks

by Aram Harrow

Dear quanta, This Friday at 11am will be our regular group meeting. Ryuji will talk about resource theories. John Napp was going to speak but will instead give a talk about gradients in variational algortihms on Wed, Nov 14, from 1:30-2:30pm. (room TBA) I'll also speak this Friday in Boaz Barak's class at Harvard: https://www.boazbarak.org/fall18seminar/ My talk will be a review of the Brandao-Kastoryano papers on preparing thermal states on quantum computers. Next Friday (Nov 16), we'll have Xun Gao from Harvard speak in our group meeting about his recent paper Efficient classical simulation of noisy quantum computation <https://arxiv.org/abs/1810.03176> . aram _______________________________________________ qip mailing list qip(a)mit.edu http://mailman.mit.edu/mailman/listinfo/qip

5 years, 5 months

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aspuru-list November 2018