Archive for quantum computers

Nature tidbits [23/05/2024]

Posted in Books, Kids, pictures, Travel, University life with tags , , , , , , , , , , , , , , , , , , , , , on August 12, 2024 by xi'an

When visiting Warwick last week, I read an issue of Nature in the plane and came across…

…a brand new and ambitious museum in Egypt for Egyptians (and others), incl. the repatriation of many artefacts, while hoping the tragedy of the unique Institute of Egypt, a research centre set up in 1798 by Bonaparte, being destroyed in 2011 by fire during the clashes between Tahrir Square protestors and military forces in Cairo, and finished by firemen flooding the place and its rare books, and remembering the sorry state of the surroundings of the Great Pyramids when I visited them almost twenty years ago,
…Nature editorial on its failing to publish AlphaFold3 code, with corporate knee-jerk newspeak,
…within an article on the “miracle” obesity drug(s), the sobering warning of half of the population turning obese by 2035…
…a Swiss experiment on paying researchers to spot errors in published papers, although I am unconvinced by the argument that paid readers would prove more reliable than benevolent ones,
…AI experts hired by the US Congress providing advice on federal AI legislation,
new achievements in developing quantum internet at the scale of a (so far small) city, a concept I had never met before (and which does not make total sense to me, incl. the appeal of quantum entanglement),
…support or lack thereof of harassed scientists within their institution (which would clearly be in the “lack” branch for my institution!),
…some “careers stories” of faith vs. science, that reports on a survey on how scientists with a religious affiliation experience their religion at work, or not, with some unconvincing arguments towards incorporating religion elements in scientific discussions,
…a (weekly) portrait of a biotechnologist cum fisherman fishing for blue crabs in Pula, Croatia—which we visited eleven years ago—,  an invasive species that he encourages people to eat,

and much more stuff!

JSM 2024, Portland, Day 1

Posted in pictures, Running, Statistics, Travel, University life with tags , , , , , , , , , , , , , , , , , , , , , , , , , , on August 6, 2024 by xi'an

Strolling through the Oregon Conference Centre on 5 Aug, I am as always amazed at how the JSM conference centres have the ability to swallow in thousands of participants without giving an impression of overcrowding! (And appreciating the moderate air conditioning, which for once does not require wearing a fleece indoors!), I must admit that my first impressions of the city itself have been rather poor, as I was (unsuccessfully) seeking an after-hour grocery near the conference centre, I walked through run-down areas and kept passing homeless people, most in a sorry state. And hearing throughout the night, And again this morning in the warehouse maze I jogged through  before hitting the Willamette River path, which goes uninterrupted for miles. And showed me an unexpected spot, the Kevin Duckworth dock, where swimming the Willamette is feasible. Hopefully attempting a morn swim before I leave Portland.

I attended the quantum computing session, with a rather light introduction without bringing much light on the nature of qubits for storage and computing. In particular, the role of the complex coefficients of the 0 and 1 states. Then my friend Brani Vidakovic gave us an hand-on demonstration (almost hand-on as the conference facilities were unable to let a code run live!, eons away from quantum performances!!). Using Qiskit and Anaconda. He pointed out that measuring a qubit is destroying its quantum nature, the very equivalent of Schrôdinger’s cat. But does not make it clear whether or not the qubit later returns to a random entity, since frequency stabilisation is assumed, witness the histograms displayed by Brani. or a Nature paper of last year.

Went to a (poorly attended) privacy panel session next. With a defence of the value of differential privacy (Jordan Awan, Purdue) somewhat connected with our own (Ocean) work, although utility not understood in a decision-theoretic sense. And privacy remaining in an one-suits-all sense. With Michael Hawes from the US Census Bureau introducing more dimensions than mere DP (coarsening, suppression, swapping, &tc.), with legal aspects (Title 13) of disclosure risk. With the positive (for me) notion of providing a meaningful assessment of disclosure, with some records being more vulnerable than others. And another one on the cumulative disclosure risk over time. If short in quantitative entries. With Valbona Bejleri (USDA NASS, with a Census of their own) on cell suppressions and metrics for assessing disclosure, eg Shannon’s information entropy. And with Gary Howarth (Privacy Engineering Program, NIST). whose point remained rather unclear to me, like the apparently obvious point that adding features increase dispersion between populations. Although presenting tools for convincing experts and actors of the efficiency of privacy protection techniques.

Which continued (sort of) on the afternoon with a synthetic data for preserving privacy panel session. With Bradley Malin (Vanderbilt U) on the dangers of (Nature Communication paper of 2022). And Harrison Quick using a posterior predictive to achieve differential privacy, albeit considering the posterior predictive as the statistical analysis outcome does not seem the right focus (and recoup my earlier criticism of differential privacy requiring bending one’s prior beliefs). Indeed, as a Bayesian aiming at inference rather than merely at not releasing raw data, I would use synthetic data generated from that posterior predictive to return a posterior on the parameters of interest. And Joshua Snoke (RAND) with cautionary warnings. Like producing “invalid” inference because the reliance on a specific model (but isn’t that the case for most of statistics?). And Roee Gutman (Brown U), discussing the special case of record linkage. More into the difficulties in creating synthetic data. (Like the issue with missingness.) Somehow disappointing in not reaching a more statistical and quantitative perspective, eg by sticking to a Bayesian perspective the whole way.

On a non-technical side, I am surprised at hardly anyone adopting the bring-your-own-container policy in the OCC cafés, or outside, given the large number of attendees carrying one or several liquid containers.

quantum computing reproducibility crisis?

Posted in Books, Statistics, Travel, University life with tags , , , , , , , , on September 16, 2021 by xi'an

While standing in a train to my mother’s house in Brittany, I was catching up on earlier Nature issues and came upon this April issue where, following the retraction of a Nature paper on the topic, Sergey Frolov casts doubt on the possible detection of a new type of quantum particle, the Majorana fermion, whose existence still remains inconclusive. The criticism concentrates on the data analysis of signals where the appearance of a narrow peak should support the hypothesised existence. The article is interesting (to me) as a reflection of someone having published positive, then negative articles on the topic, upon the tendency for authors in the field to cherry-pick experiments where some peaks occur. Among dozens or hundred of experiments where they did not. And calling for open data and more stringent review(er)s on the matter (and others). The arguments in the opinion tribune sound most reasonable but I wonder whether or not other particle physicists share the same concern.

certified randomness, 187m away…

Posted in Statistics with tags , , , , , , , on May 3, 2018 by xi'an

As it rarely happens with Nature, I just read an article that directly relates to my research interests, about a secure physical random number generator (RNG). By Peter Bierhost and co-authors, mostly physicists apparently. Security here means that the outcome of the RNG is unpredictable. This very peculiar RNG is based on two correlated photons sent to two measuring stations, separated by at least 187m, which have to display unpredictable outcomes in order to respect the impossibility of faster-than-light communications, otherwise known as Bell inequalities. This is hardly practical though, especially when mentioning that the authors managed to produce 2¹⁰ random bits over 10 minutes, post processing “the measurement of 55 million photon pairs”. (I however fail to see why the two-arm apparatus would be needed for regular random generation as it seems relevant solely for the demonstration of randomness.) I also checked the associated supplementary material, which is mostly about proving some total variation bound, and constructing a Bell function. What is most puzzling in this paper (and the associated supplementary material) is the (apparent) lack of guarantee of uniformity of the RNG. For instance, a sentence (Supplementary Material, p.11) about  a distribution being “within TV distance of uniform” hints at the method being not provably uniform, which makes the whole exercise incomprehensible…

Nature snapshots [and snide shots]

Posted in Books, pictures, Statistics, Travel, University life with tags , , , , , , , , , , , on October 12, 2017 by xi'an

A very rich issue of Nature I received [late] just before leaving for Warwick with a series of reviews on quantum computing, presenting machine learning as the most like immediate application of this new type of computing. Also including irate letters and an embarassed correction of an editorial published the week before reflecting on the need (or lack thereof) to remove or augment statues of scientists whose methods were unethical, even when eventually producing long lasting advances. (Like the 19th Century gynecologist J. Marion Sims experimenting on female slaves.) And a review of a book on the fascinating topic of Chinese typewriters. And this picture above of a flooded playground that looks like a piece of abstract art thanks to the muddy background.

“Quantum mechanics is well known to produce atypical patterns in data. Classical machine learning methods such as deep neural networks frequently have the feature that they can both recognize statistical patterns in data and produce data that possess the same statistical patterns: they recognize the patterns that they produce. This observation suggests the following hope. If small quantum information processors can produce statistical patterns that are computationally difficult for a classical computer to produce, then perhaps they can also recognize patterns that are equally difficult to recognize classically.” Jacob Biamonte et al., Nature, 14 Sept 2017

One of the review papers on quantum computing is about quantum machine learning. Although like Jon Snow I know nothing about this, I find it rather dull as it spends most of its space on explaining existing methods like PCA and support vector machines. Rather than exploring potential paradigm shifts offered by the exotic nature of quantum computing. Like moving to Bayesian logic that mimics a whole posterior rather than produces estimates or model probabilities. And away from linear representations. (The paper mentions a O(√N) speedup for Bayesian inference in a table, but does not tell more, which may thus be only about MAP estimators for all I know.) I also disagree with the brave new World tone of the above quote or misunderstand its meaning. Since atypical and statistical cannot but clash, “universal deep quantum learners may recognize and classify patterns that classical computers cannot” does not have a proper meaning. The paper contains a vignette about quantum Boltzman machines that finds a minimum entropy approximation to a four state distribution, with comments that seem to indicate an ability to simulate from this system.