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Jonathan Oppenheim @postquantum.bsky.social · 1d

I think there are several differences but indeed the non linearity is due to this back reaction and feedback. There are observable consequences eg share.google/dmi6mVvwkdCA...

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Jonathan Oppenheim @postquantum.bsky.social · 2d

And visa versa, both systems act and react to each other. This follows from two of the axioms.

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Jonathan Oppenheim @postquantum.bsky.social · 2d

Crucially, the quantum state remains pure at all time, conditioned on the classical trajectory. No decoherence! One world, not many. Both systems trace a single definite (but unpredictable) path through their configuration spaces. 5/5

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Jonathan Oppenheim @postquantum.bsky.social · 2d

Now here's the remarkable part: we just apply standard classical probability theory to the classical system.
Using a change of measure (standard tool from finance/probability), and the Born rule ( |ψ|²)emerges automatically. No measurement postulate needed. No many worlds. 4/5

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Jonathan Oppenheim @postquantum.bsky.social · 2d

A natural candidate for the classical system? Spacetime itself. Quantum field theory appears to require a classical spacetime to be well defined. E.g. we demand [φ(x),φ(y)]=0 for spacelike separated points. But "spacelike" presupposes a definite causal structure—a classical spacetime metric.
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Jonathan Oppenheim @postquantum.bsky.social · 2d

Joint work with Isaac Layton and Zachary Weller-Davies.

We propose a few simple axioms:
- A classical system exists.
- Quantum systems evolve linearly.
- Their interaction may be stochastic.
- The interaction depends on the current quantum state.
- No preferred basis.
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Jonathan Oppenheim @postquantum.bsky.social · 2d

What if the measurement problem isn't about explaining how the classical world emerges from the quantum world...

...but about what happens when quantum systems interact with something that's already classical?

Turns out, the collapse postulate + Born rule emerge!
scirate.com/arxiv/2510.0...
🧪⚛️🧵1/5

A one-world interpretation of quantum mechanics

The measurement problem is the issue of explaining how the objective classical world emerges from a quantum one. Here we take a different approach. We assume that there is an objective classical syste...

scirate.com

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Jonathan Oppenheim @postquantum.bsky.social · 5d

Renyi divergences emerge when agents bet (or "invest" as some people call it), over a finite number of rounds. In the limit of an infinite number of bets we recover the Kelly Criterion, given in terms of Relative entropy distances (KL divergences). Such a fun project! 4/4

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Jonathan Oppenheim @postquantum.bsky.social · 5d

And it allows us to extend gambling into other settings (like thermodynamics) and into the quantum domain where we use it to quantify what it means for competing agents to know more in a quantum world. 3/

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Jonathan Oppenheim @postquantum.bsky.social · 5d

scirate.com/arxiv/2510.08418 and scirate.com/arxiv/2510.0... with Renato Renner, Takahiro Sagawa, and Philippe Faist. We find a risk–reward trade-off governed by Rényi divergences. The resource theory framework unifies gambling, utility theory, and hypothesis testing. 2/

A resource theory of gambling

Betting games provide a natural setting to capture how information yields strategic advantage. The Kelly criterion for betting, long a cornerstone of portfolio theory and information theory, admits an...

scirate.com

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Jonathan Oppenheim @postquantum.bsky.social · 5d

Maite Arcos's PhD results are hitting the arxiv! A resource theory of gambling, and a paper on adversarial thermodynamics are out today. Gambling provides an operational way to quantify who has more information. And it can be extended into the quantum domain!🧵🧪⚛️ 1/

Maite Arcos (left), Charlie Bennett (center), Lluis Masanes (right)

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Reposted by Jonathan Oppenheim

John Preskill @preskill.bsky.social · 20d

6,100 neutral-atom qubits trapped in a grid by lasers @caltech.edu ... is a lot.

www.caltech.edu/about/news/c...

Caltech Team Sets Record with 6,100-Qubit Array

The neutral-atom platform shows promise for scaling up quantum computers.

www.caltech.edu

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Jonathan Oppenheim @postquantum.bsky.social · 20d

They sure take electromagnetism seriously in @quantumaephraim.bsky.social's lab!

Quantum optics table with Nick Mantella's muscle in the foreground and his Maxwell eqn tattoo.

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Reposted by Jonathan Oppenheim

FQxI @fqxi.org · Sep 3

In a recent Substack post, FQxI's Jonathan Oppenheim discusses how far #LLMS have progressed. @postquantum.bsky.social says "their answers often look very convincing on the surface until you go through them more carefully".
DISCUSS: forums.fqxi.org/d/4283-how-g...

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Jonathan Oppenheim @postquantum.bsky.social · Sep 3

The CERN whitepaper, on testing the quantum nature of gravity, has even more co-authors and is now available on the arxiv, scirate.com/arxiv/2509.0.... Check it out! 🧪⚛️

A Spin-Based Pathway to Testing the Quantum Nature of Gravity

A key open problem in physics is the correct way to combine gravity (described by general relativity) with everything else (described by quantum mechanics). This problem suggests that general relativi...

scirate.com

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Reposted by Jonathan Oppenheim

Nature @nature.com · Aug 13

There is one fundamental phenomenon that quantum physics can't explain: gravity

go.nature.com/45v70f1

Is gravity quantum? Experiments could finally probe one of physics’ biggest questions

Physicists are developing laboratory tests to give insight into the true nature of gravity.

go.nature.com

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Jonathan Oppenheim @postquantum.bsky.social · Jul 8

I'm at the African Institute for Mathematical Science Ghana this week for a quantum hackathon. Which is apparently called a Quantathon! Excited to interact with great students and researchers from across Africa. Live feed at t.co/J8UzPKc6Vx & schedule at qtedu.aims.edu.gh. Public lecture on Friday.

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Reposted by Jonathan Oppenheim

David Rankin @asteroiddave.bsky.social · Jul 2

FACT THREAD on New Interstellar Object #A11pl3Z

This story unfolded pretty fast yesterday for a few reasons. The object was discovered on July 1st UTC by the Asteroid Terrestrial-impact Last Alert System, or ATLAS team. A #NASA funded survey at the University of Hawaii. atlas.fallingstar.com 🔭🧪

Orbit diagram of interstellar object A11pl3Z

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Reposted by Jonathan Oppenheim

Chris Lintott @chrislintott.bsky.social · Jul 2

!!!!! Waking up to the news that we might have found an interstellar object passing through our Solar System - only the third ever seen. Looks convincing based on the orbit.

Michael Busch @michael-w-busch.bsky.social · Jul 2

For any asteroid observers who have not heard about it already:

Newly-discovered #A11pl3Z is a candidate interstellar object.

cneos.jpl.nasa.gov/scout/#/obje...

Scout: NEOCP Hazard Assessment

NASA's Near-Earth Object (NEO) web-site. Data related to Earth impact risk, close-approaches, and much more.

cneos.jpl.nasa.gov

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Reposted by Jonathan Oppenheim

Dan Garisto @dangaristo.bsky.social · Jun 24

NEW: NSF will be kicked out of their building. Announcement will be made tomorrow by HUD Sec. and Governor of VA. HUD will take over the NSF building over the next two years.

NSF staffer: "There is no planning for NSF, no identified future location, appropriation for a new building or a move."

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Reposted by Jonathan Oppenheim

Katie Mack @astrokatie.com · Jun 24

Just click on this: skyviewer.app/explorer #RubinTelescope

Explorer | Skyviewer

skyviewer.app

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Jonathan Oppenheim @postquantum.bsky.social · Jun 21

Sad news, Ray was both a a really kind man and a great scientist.

Aephraim Steinberg @quantumaephraim.bsky.social · Jun 21

RIP Ray Laflamme, gone too soon.

Ray was a stellar scientist, the founding director of ⁦‪the IQC‬⁩ and ⁦‪of CIFAR's‬⁩ Quantum Information program, but more importantly a warm & generous human who built community and helped many (particularly junior researchers).

May his memory be a blessing.

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Jonathan Oppenheim @postquantum.bsky.social · Jun 16

Bluesky has just changed the messaging you get when you hit "show less like this" to make it clear that you're giving feedback to the feed curator. While I just want to tweak what I see, not what everyone else sees...

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Jonathan Oppenheim @postquantum.bsky.social · Jun 13

But I generally prefer the Discover feed. Surely it isn't difficult to make the "show less like this" tag actually do something? Or perform some machine learning based on what I interact with. I've tried some of the other feeds, but haven't yet found one that works for me.

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Reposted by Jonathan Oppenheim

Quanta Magazine @quantamagazine.bsky.social · Jun 13

What if gravity isn’t a pull from mass, but a push from entropy? @georgemusser.com reports on the latest version of an old idea.

www.quantamagazine.org/is-gravity-j...

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