aspuru-list

aspuru-list@lists.fas.harvard.edu

7234 discussions

[Aspuru-Guzik Group List] [qip] group meeting and afternoon talk tomorrow

by Aram Harrow

Dear quanta, Tomorrow at 11am we will meet in 6-310 and our visitor Ulysse Chabaud will tell us about his recent work on the stellar representation of non-Gaussian states. https://arxiv.org/abs/1907.11009 At 1:30pm, Giacomo will give a talk in 6c-402 about optimal transport in quantum systems. https://arxiv.org/abs/1911.00803 -aram _______________________________________________ qip mailing list qip(a)mit.edu http://mailman.mit.edu/mailman/listinfo/qip

4 years, 6 months

[Aspuru-Guzik Group List] [qip] Ulysse Chabaud visit

by Aram Harrow

Dear quanta, Ulysse Chabaud is visiting us from Paris 6 from this afternoon through Friday. He'll speak on Friday about "the stellar representation of non-Gaussian states" and his other work is generally on the continuous-variable side of quantum information. If you would like to meet him, you can either email me, or write him directly at ulysse.chabaud(a)gmail.com. He'll be in 6-308 while here. His papers are here: https://scholar.google.com/citations?user=ro1eG-EAAAAJ&hl=fr -aram _______________________________________________ qip mailing list qip(a)mit.edu http://mailman.mit.edu/mailman/listinfo/qip

4 years, 6 months

[Aspuru-Guzik Group List] Joint Quantum Seminar - Wednesday, November 13 @ 12PM - Prof. Michelle Simmons

by Ploucha, Clare

Joint Quantum Seminar Wednesday, November 13 12 PM, Jefferson 250 *PLEASE NOTE SPECIAL TIME* Michelle Simmons - Centre of Excellence for Quantum Computation and Communication Technology, University of New South Wales Atomic qubits in silicon Abstract: Building a quantum computer in the highly manufacturable material silicon offers many advantages. Phosphorus atom qubits in silicon in particular have demonstrated extremely long (up to 35 s) coherence times with >99.9% fidelity. Their small size, combined with the magnetically quiet environment of isotopically pure silicon, make them analogous to ion trap qubits but in a scalable solid-state system. One of the challenges for semiconductor qubits is to understand how to engineer and control qubit initialisation, read-out and coupling at nm length scales. Scanning probe techniques, combined with molecular beam epitaxy allow us to realise fully crystalline devices at the atomic scale and directly probe the qubit wave function with exquisite precision. We will discuss the ability to scale atomic qubits and long term vision for this approach.

4 years, 6 months

[Aspuru-Guzik Group List] [qip] talks Friday

by Aram Harrow

Dear quanta, In our Friday group meeting we will have a talk from Kyungjoo Noh (Yale) on bosonic codes. That afternoon (1:30pm, 6c-402) we will have a talk by Tongyang Li (Maryland); information below. Title: Quantum algorithm for estimating volumes of convex bodies https://arxiv.org/abs/1908.03903 Abstract: Estimating the volume of a convex body is a central problem in convex geometry and can be viewed as a continuous version of counting. We present a quantum algorithm that estimates the volume of an $n$-dimensional convex body within multiplicative error $\epsilon$ using $\tilde{O}(n^{3}+n^{2.5}/\epsilon)$ queries to a membership oracle and $\tilde{O}(n^{5}+n^{4.5}/\epsilon)$ additional arithmetic operations. For comparison, the best known classical algorithm uses $\tilde{O}(n^{4}+n^{3}/\epsilon^{2})$ queries and $\tilde{O}(n^{6}+n^{5}/\epsilon^{2})$ additional arithmetic operations. To the best of our knowledge, this is the first quantum speedup for volume estimation. Our algorithm is based on a refined framework for speeding up simulated annealing algorithms that might be of independent interest. This framework applies in the setting of "Chebyshev cooling", where the solution is expressed as a telescoping product of ratios, each having bounded variance. We develop several novel techniques when implementing our framework, including a theory of continuous-space quantum walks with rigorous bounds on discretization error. _______________________________________________ qip mailing list qip(a)mit.edu http://mailman.mit.edu/mailman/listinfo/qip

4 years, 6 months

[Aspuru-Guzik Group List] [qip] talks this week

by Aram Harrow

*Today: * see Ramis's email for a talk starting shortly on tensor networks for spin chains. *Tuesday* There is a seminar on generalizations of Haah's cubic code and implications for topological order. *CMT Informal Seminar <http://web.mit.edu/physics/cmt/informalseminar.html>*Tuesday, October 29, 2019 at 12:00 PM in 4-331 Meng Cheng, Yale University "Exploring 3D fracton topological order: gauged layers construction and entanglement renormalization" There is also a talk on color centers in diamond. *CUA Seminar <http://www.rle.mit.edu/cua_responsive/event-type/cua-seminar-series/>* Tuesday, October 29, 2019 at 4:00pm in MIT 4-270 Nathalie de Leon, Princeton "Engineering coherent defects in diamond" Ten Minute Talk: "Laser-cooled polyatomic molecules for precision measurement" by Zack Lasner *Wednesday* I will speak at Harvard's "random matrix and probability" seminar at 3:15pm in the CMSA (20 Garden St) room G02. http://cmsa.fas.harvard.edu/rm-and-pt/ My talk will be about my work on 2-D random circuits with Saeed as well as John, Rolando, Alex Dalzell and Fernando Brandao. *Thursday* Opportunities and Challenges for Spin Qubits in Silicon Ed Chen, HRL 6C-442, 12pm Quantum information processing aims to leverage the properties of quantum mechanics to manipulate information in ways that are not otherwise possible. This would enable, for example, quantum computers that could solve certain problems exponentially faster than a conventional supercomputer. One promising approach for building such a machine is to use gated silicon quantum dots. In the approach taken at HRL Laboratories, individual electrons are trapped in a gated potential well at the barrier of a Si/SiGe heterostructure. Spins on these electrons are compelling candidates for qubits due to their long coherence times, all-electrical control, and compatibility with conventional fabrication techniques. In this talk, I will discuss our recent demonstrations of automated tune-up of a six-dot Si device into a configuration suitable for high-fidelity, randomized benchmarking of exchange-only qubits. References: 1. RW Andrews et al. Nature Nanotechnology, 14 (8), 747-750 (2019) 2. AM Jones, et al. Physical Review Applied, 12 (1), 014026 (2019) 3. SM Meenehan (HRL). APS March Meeting, X34.00004 (2019) You should all be on the iquise list, so you that you would also know about their 3pm social on Thursday. *Friday* We will resume our group meetings and have a talk from Sultana Tokhy. (11am, 6-310). Title: Decoding Approximate Holographic Quantum Error Correcting Codes Abstract: Holographic theories of quantum gravity are some of the most successful marriages of quantum information theory and gravitational physics. Most notably, the AdS/CFT (Anti de Sitter/Conformal Field Theory) correspondence is a duality between a conformal field theory (CFT) in flat spacetime and a theory of (quantum) gravity in one higher dimension. Since the two theories are dual, all the information in the bulk spacetime can be represented in one fewer dimension, reminiscent of an optical hologram. Recently, AdS/CFT has been reinterpreted using the language of quantum error correction. Toy models of these holographic quantum codes have been proposed using tensor network models; one such network (known as the HaPPY code) is based on the well-known 5 qubit code. Continuous variable analogs of the HaPPY code have also been proposed, some of which have the property of being U(1) covariant codes. Independently of AdS/CFT, it is known that finite dimensional covariant codes cannot be perfectly error correcting, and bounds on the quality of such a code have been placed. In this work, we built simulations of both the 5 qubit HaPPY code and a U(1) covariant, continuous variable generalization of the HaPPY code. Our simulation uses the recently released TensorNetwork Python library. In addition to building the holographic tensor network, we also implement explicit decoders for each of the codes, as well as the so-called Petz map and twirled Petz map recovery channels. We then compare the recovery fidelity using each of these decoding methods to one another and, in the case of the covariant codes, to the known bounds on the quality of approximate covariant codes. Our results can help inform the development of more realistic, continuous variable tensor network toy models of AdS/CFT. In the afternoon (1:30pm, 6C-442) we will have a talk by Nicole Yunger Halpern. title: Noncommuting conserved charges in quantum many-body thermalization In statistical mechanics, a small system exchanges conserved charges—heat, particles, electric charge, etc.—with a bath. The small system may thermalize to the canonical ensemble, or the grand canonical ensemble, etc. The charges are usually represented by operators assumed implicitly to commute with each other. But noncommutation distinguishes quantum physics from classical. What if the operators fail to commute? A “non-Abelian thermal state” was derived recently in the abstract, idealized framework of quantum-information thermodynamics. Meanwhile, quantum many-body thermalization has undergone a renaissance in high-energy physics; condensed matter; and atomic, molecular, and optical physics: Toolkits including the eigenstate thermalization hypothesis (ETH), random unitary circuits, and out-of-time-ordered correlators have been developed. These tools call for generalizing and application to nonclassically noncommuting charges. We bridge noncommuting charges from quantum-information thermodynamics to many-body physics: We extend the ETH, propose a protocol for realizing the non-Abelian thermal state experimentally, and test the protocol with numerical simulations of a spin chain. The protocol is suited to ultracold atoms, trapped ions, and quantum dots. I will close with the opportunities engendered for many-body physics by noncommuting charges. *References* NYH, Beverland, and Kalev, arXiv:1906.09227 (2019) https://arxiv.org/abs/1906.09227. NYH, Faist, Oppenheim, and Winter, Nat. Comms. 7, 12051 (2016) https://www.nature.com/articles/ncomms12051. NYH, J. Phys. A 51, 094001 (2018) https://iopscience.iop.org/article/10.1088/1751-8121/aaa62f/meta. _______________________________________________ qip mailing list qip(a)mit.edu http://mailman.mit.edu/mailman/listinfo/qip

4 years, 6 months

[Aspuru-Guzik Group List] Joint Quantum Seminar - TODAY - Prof. Angel Rubio

by Ploucha, Clare

Joint Quantum Seminar Wednesday, October 30 4:00 PM, Jefferson 250 Angel Rubio, Max Planck Institute for the Structure and Dynamics of Matter; Center for Computational Quantum Physics “Quantum Cavities and Floquet Materials Engineering from First Principles QEDFT” An appealing and challenging route towards engineering materials with specic properties is to find ways of designing or selectively manipulate materials, especially at the quantum level. We will provide an overview of how well-established concepts in the fields of quantum chemistry and materials have to be adapted when the quantum nature of light becomes important. We will pursue the question whether it is possible to create these new states of materials as groundstates of the system. To this end we will show how the emerging (vaccum) dressed states resembles Floquet states in driven systems. A particular appeal of light dressing is the possibility to engineer symmetry breaking which can lead to novel properties of materials, e.g coupling to circularly polarized photons leads to local breaking of time-reversal symmetry enabling the control over a large variety of materials properties (e.g.topology). We show that the new quantum electrodynamics density-functional formalism (QEDFT) can account for those effects. We illustrate the realization of those ideas in molecular complexes and 2D materials. 4:00 pm: Ten Minute Talk by Pavel Dolgirev (Demler group) 4:15 pm: Refreshments 4:30 pm: Prof. Angel Rubio -- Clare Ploucha Director of Programs Harvard Quantum Initiative 18 Hammond Street, Palfrey 105 Cambridge, MA 02138

4 years, 6 months

[Aspuru-Guzik Group List] Joint Quantum Seminar - Wednesday, October 30 @ 4:00 - Prof. Angel Rubio

by Ploucha, Clare

4 years, 6 months

[Aspuru-Guzik Group List] [qip] talks on Friday

by Aram Harrow

Dear quanta, Henry Yuen (Toronto) will be visiting and giving the crypto seminar this Friday from 10:30-12 in room G882 in the Stata center, titled "Perfect zero knowledge for quantum multiprover interactive proofs" and based on https://arxiv.org/abs/1905.11280 . Because this should interest a lot of the group, we will cancel the group meeting. We also have Nayeli A. Rodríguez Briones (Waterloo) visiting and she will speak at 1:30pm on Friday in 6C-442. The title is "Enhanced Heat-Bath Algorithmic Cooling" Abstracts below ---------- Henry Yuen Perfect zero knowledge for quantum multiprover interactive proofs https://toc.csail.mit.edu/node/1353 In a seminal 1988 paper, Ben-Or, Goldwasser, Kilian, and Wigderson (BGKW) introduced the model of multiprover interactive proofs (MIPs), and furthermore showed that zero knowledge can always be attained in this model without computational assumptions. Their paper has been enormously influential across cryptography and complexity theory, inspiring much research into zero knowledge, interactive proofs, PCPs, delegated computation, and more. In 2004, Cleve, Hoyer, Toner, and Watrous introduced the model of quantum multiprover interactive proofs (QMIPs), which are MIPs where the provers are allowed to share quantum entanglement (but still cannot communicate). The study of QMIPs has similarly been extremely fruitful in both quantum complexity theory and quantum cryptography. In this work, we prove the quantum analogue of BGKW's result: we show every quantum multiprover interactive proof can be transformed into an equivalent protocol that has the zero knowledge property. Since recent work has shown that QMIPs are capable of deciding extremely complex languages (such as nondeterministic *doubly-exponential* time), our result implies that such languages also have (quantum) zero knowledge proofs. The main techniques used in this paper is a procedure to compress quantum interactive protocols, and quantum error correcting codes. I will keep this talk self-contained and accessible; in particular I will not assume any background in quantum information. ----------- Nayeli A. Rodríguez Briones Quantum information science has shown that energy transport and information processing are two sides of the same coin, inspiring interesting methods for cooling physical systems by processing their information at the quantum scale, such as heat-bath algorithmic cooling. These cooling mechanisms not only provide fundamental insights into quantum thermodynamics, but they also give practical methods to increase the purity of qubits. Highly pure qubits are required as the initial state in most of the quantum algorithms, and provide a reliable low-noise supply of ancilla qubits for quantum error correction. In this talk, I will first review the basic ideas of algorithmic cooling and give analytical results for the achievable cooling limits of the conventional heat-bath version. Then, I show how the limits can be circumvented by taking advantage of correlations created during the rethermalization step, and correlations present in the initial state induced by the internal interactions of the system. I present two new algorithmic cooling methods to show explicitly how correlations can be used to enhance cooling. _______________________________________________ qip mailing list qip(a)mit.edu http://mailman.mit.edu/mailman/listinfo/qip

4 years, 6 months

[Aspuru-Guzik Group List] [qip] crypto talk today

by Aram Harrow

Today at 2pm Chris Peikert is speaking in the G5 lounge at Stata on the following paper that comes up with a quantum attack on CSIDH, one of the NIST proposals. https://eprint.iacr.org/2019/725 By the way, you should all be on the iquise list as well. Today's talk, for example, is Quantum Information Theoretic Methods in Inflationary Cosmology by Achim Kempf. -aram _______________________________________________ qip mailing list qip(a)mit.edu http://mailman.mit.edu/mailman/listinfo/qip

4 years, 7 months

[Aspuru-Guzik Group List] [qip] upcoming group meetings

by Aram Harrow

Dear quanta, This Wed-Fri is the Harvard workshop I've mentioned before. The schedule is now up: http://cmsa.fas.harvard.edu/noncommutative-analysis/ Since many of us will be there, I propose skipping this Friday's group meeting. Here are speakers lined up for future weeks: Oct 25 group meeting: Nayeli Rodríguez-Briones (Waterloo) Enhanced Heat-Bath Algorithmic Cooling Nov 1 group meeting: Sultana Tokhy (Arizona State) Decoding Approximate Holographic Quantum Error Correcting Codes Nov 1 seminar: Nicole Yunger Halpern Nov 8 group meeting: Kyungjoo Noh (Yale) on bosonic QECCs Nov 8 seminar: Tongyang Li (Maryland) Quantum algorithm for estimating volumes of convex bodies Please let me know if you'd like to speak in a future week or have suggestions. -aram _______________________________________________ qip mailing list qip(a)mit.edu http://mailman.mit.edu/mailman/listinfo/qip

4 years, 7 months

← Newer
1
...
4
5
6
7
8
9
10
...
724
Older →

Jump to page:

2024

2023

2022

2021

2020

2019

2018

2017

2016

2015

2014

2013

2012

2011

2010

2009

2008

2007

2006

aspuru-list