
Theoretical physicist @Caltech, Director of @IQIM_Caltech
Pasadena, California
Joined October 2010
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John Preskill retweeted
In our new work, we touch one of the beautiful fundamental questions at the heart of quantum physics: when does classical behavior emerge from quantum systems?
We study this question through the lens of learning bosonic Gaussian states, and find a precise quantum-to-classical crossover in their learnability as thermal fluctuations increase. Cold Gaussian states are intrinsically quantum to learn, while sufficiently warm ones can be learned with the same sample complexity as classical Gaussian distributions, using operations that are just as simple.
Thanks a lot to my collaborators @CSenrui, @FrancescoMeleAn, and @preskill for all their great work! I'm also grateful for my visit to Caltech in March, where I had the nice opportunity to brainstorm this project in person with them!
ArXiv link: arxiv.org/pdf/2609.26705
John Preskill retweeted
We're pleased to announce the QIP 2027 call for submissions. The key dates are as follows; refer to the website qipconference.org/2027/call/ for detailed instructions.
John Preskill retweeted
Welcome feedback on my new quantum disclosure law & tech policy paper. Thanks to @Preskill for helpful input.
SSRN: papers.ssrn.com/sol3/papers.…
#QuantumComputing #QuantumCryptography #PostQuantumCryptography #Cybersecurity #TechnologyPolicy #LawTech #BerkeleyLaw #StanfordLaw
John Preskill retweeted
I learned about @MarkWiseSays from John Preskill's eulogy for Mark. I heard all the tweets in his voice; and I laughed so hard, I cried. @preskill xitter.cf/preskill/status/207849…
John Preskill@preskillJul 18United States
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My friend Mark Wise
quantumfrontiers.com/2026/07…
John Preskill retweeted
this is a timely talk with the whole research community (at least in QIP) currently pondering this very question:
"How to Respond to the Automation of Research"
by Hsin-Yuan Huang @RobertHuangHY (Caltech & @TeamOratomic )
John Preskill retweeted
We at @khoslaventures made the largest initial investment yet, as we did in OpenAI, into @TeamOratomic after we looked at a dozen Quantum starts in a decade. On its way to solve Shor's algorithm, the true symbol of getting to "quantum computing" FIRST. oratomic.com/. Join them in building the world’s first fault-tolerant quantum computer capable of useful applications and a fundamentally new model of computation that could have consequences far beyond what we can predict today
Today, Caltech and JPL welcome renowned astrophysicist, acclaimed author, and transformative leader, Ray Jayawardhana as the Institute’s tenth president! He brings a fierce commitment to building on Caltech’s legacy of discovery and exploration.
tinyurl.com/5y3j6ebx
John Preskill retweeted
Over the recent weeks and months, @preskill and I sat down to think about where we are in quantum computing. While the noisy intermediate-scale quantum (#NISQ) era — a term coined by John in 2018 — is just unfolding as we speak, the time seems right to look ahead to the next steps to come.
scirate.com/arxiv/2510.19928
In this perspectives article, we try to sketch the fraught road to quantum advantage — the path toward fault-tolerant, application-scale quantum (#FASQ) computers. There are several gaps ahead of us, and we try to faithfully and honestly hint at how one may be able to "mind those gaps", and suggest a few important intermediate steps along the way.
I have been impressed by the ease and efficiency with which we have been able to put this together. Warm thanks to John for the great collaboration and wonderful team work.
John Preskill retweeted
Happy to see that our work with @RobertHuangHY and @preskill is now published! We use shadow overlap to make machine learning of quantum systems verifiable, and to benchmark & optimize quantum circuits.
The certification protocol presented here is an efficient way to verify that a many-qubit quantum state is close to a desired target state. As well as enabling the verification of near-term quantum devices, it has applications to quantum learning.
nature.com/articles/s41567-0…
John Preskill retweeted
Bringing our first Heron R3 QPU online: ibm_pittsburgh, inside an IBM Quantum System Two in Poughkeepsie, NY.
R3 isn’t a redesign—it’s precision refinement. And it shows:
• T1: 300 µs
• T2: 370 µs
• 2Q gate error: ~5×10⁻⁴ (our best yet)
• Layered gate error 100Q: 3.2×10⁻³
• Readout error: <5×10⁻³
ibm_pittsburgh joins the fleet soon.
John Preskill retweeted
Happy to share that some previous work with @krishnanirudh and @preskill that we call hierarchical codes (2303.04798) was recently published in Quantum! 1/10
John Preskill retweeted
I am happy to share that our work has been published in Physical Review Letters
journals.aps.org/prl/abstrac….
Many thanks to my coauthors Dariel, Adam, Manuel and @preskill for the amazing collaboration!
Quantum randomness is notoriously hard to generate.
In arxiv.org/abs/2410.05181, we create random quantum states of much higher quality by injecting cheap classical randomness, without needing additional quantum resources.
Many thanks to coauthors Dariel, Adam, Manuel, @preskill!
John Preskill retweeted
Do abstract learning processes have tangible physical consequences?
Yes! In this work, we rigorously show that the (in)ability to learn dramatically impacts the amount of physical resources required to perform certain thermodynamic tasks.
arxiv.org/abs/2504.07341
John Preskill retweeted
Blown away by the record-breaking 252 submissions to #QEC25! 🚀 Exceptional quality across theory and experiment—our community keeps raising the bar. Can’t wait to work with the PC to select an outstanding program. This conference is going to be amazing! 🎉
John Preskill retweeted
Remember to submit your work to the QEC conference! The deadline is in one week.
John Preskill retweeted
In a great session on milestones in quantum physics celebrating the @QuantumYear2025 at the @APSphysics #APSSummit25, Serge Haroche, Wolfgang Ketterle, Philip Kim, Francis Halzen and @Dorit Ahararonov present their main results, chaired by @preskill.
John Preskill retweeted
I helped plan two quantum sessions at the GPS next week & I'm really excited about them 😁
"IYQ: Milestones" chaired by John Preskill
summit.aps.org/events/MAR-N1…
"IYQ: Guided by Quantum Information" chaired by Ehud Altman
summit.aps.org/events/MAR-S1…
pls consider attending!
#APSSummit25






























