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Reposted by Dan Garisto

Carl Zimmer @carlzimmer.com · 1d

Today my @nytimes.com colleagues and I are launching a new series called Lost Science. We interview US scientists who can no longer discover something new about our world, thanks to this year‘s cuts. Here is my first interview with a scientist who studied bees and fires. Gift link: nyti.ms/3IWXbiE

nyti.ms

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Dan Garisto @dangaristo.bsky.social · 1d

Anyways, my quibbles with framing aside, I want to note what has _not_ been the star of the show, thanks mainly to some very diligent message discipline by the Nobel Committee.

Fueled by this frenzy of research activity, quantum computing has garnered massive and ever-increasing amounts of publicity and funding as companies and countries try to capitalize on the technology. Overstated claims are rampant, in many cases verging into baseless hyperbole. Quantum computers are not, in fact, going to solve climate change.

So it came as something of a surprise when the Nobel Committee for Physics avoided almost all mention of quantum computing during its announcement of this year’s physics prize. In the announcement’s official scientific background information, the topic received only two mentions. The committee’s careful message discipline paid off, and news headlines focused more on the fundamental physics and less on the buzzy application.

For many physicists, the absence of hype was a relief and the downplay of quantum computing a reasonable choice. “You can fully justify the importance of this experiment without those practical implications,” Girvin says. After all, “we don’t yet know how practical quantum computing is actually going to be.”

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Dan Garisto @dangaristo.bsky.social · 1d

What Clarke, Devoret, and Martinis showed with macroscopic quantum tunneling, is that a macroscopic amount of electrons does indeed behave like Schrödinger's paradoxical puss (here, the states are 'zero voltage' and 'some voltage', instead of 'alive' and 'dead').

What Clarke, Devoret and Martinis showed is that even macroscopic reality can be blurred if it is shielded from direct contact with the wider environment. By isolating their electrons from noise and staying at ultralow temperatures, they were able to bring the foggy indeterminacy of quantum mechanics into a circuit one could hold in the palm of a hand. “It’s quantum mechanics all the way up,” Girvin says.

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Dan Garisto @dangaristo.bsky.social · 1d

Schrödinger—at least when he proposed the thought experiment—would have said no. Cats don't exist as a linear combination between 'dead' and 'alive' and neither should 10^17 electrons. (A cat, for the record, is about 10^26 electrons.)

When Schrödinger proposed his thought experiment in 1935, he had meant it as a critique of the seemingly paradoxical conclusions quantum mechanics implied about the classical world. Unlike a particle in superposition, a cat could not actually be blurred between being “dead” and “alive.” Any confusion about the cat’s state could be addressed by a direct measurement. “That prevents us from so naively accepting as valid a ‘blurred model’ for representing reality,” Schrödinger wrote at the time, according to a translation by physicist John D. Trimmer. “There is a difference between a shaky or out-of-focus photograph and a snapshot of clouds and fog banks.”

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Dan Garisto @dangaristo.bsky.social · 1d

This is really the heart of it: If you have a huge number of electrons, will they really maintain a superposition?

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Dan Garisto @dangaristo.bsky.social · 1d

The laureates reiterated this in 2020. The goal wasn't to observe tunneling, or to see a macroscopic quantum phenomena, but to see a 'macroscopic degree of freedom' with quantum properties—that is, the cat's paradoxical superposition of dead & alive.

www.nature.com/articles/s41...

Do macroscopic degrees of freedom obey quantum mechanics? During the first six decades of quantum mechanics the answer to this question was never addressed experimentally. Quantum mechanics was known to survive at the macroscopic level only through collective phenomena such as superfluidity, superconductivity, flux quantization and the Josephson effect. Although these phenomena are conventionally described as ‘macroscopic’, they are in fact classical manifestations on a macroscopic scale of the combination of large numbers of microscopic variables, each governed by quantum mechanics. The faceting of certain crystals, such as quartz, revealing the covalent bonds between constituent atoms, represents an elementary example of this class of quantum phenomena exhibited on a macroscopic scale.

In 1980, Anthony Leggett1 emphasized the importance of distinguishing macroscopic quantum phenomena originating in the somewhat trivial large-scale accumulation of effects originating at the level of microscopic variables from those displayed, hypothetically, by a single macroscopic, collective degree of freedom. Although nothing in theory would seem to prevent such variables from fully obeying quantum mechanics, we felt challenged to see if it really was the case in practice.

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Dan Garisto @dangaristo.bsky.social · 1d

One surprise for me: how explicitly the search was really tied to Schrödinger's thought experiment. Here's Leggett in 1980, and Clarke, Devoret, & Martinis citing him, front and center in their discovery paper:

However, there is a much more subtle and interesting sense in which
the question can be interpreted. To motivate this interpretation it is necessary
to recall one of the most famous paradoxes in the foundations of quantum
mechanics, the so-called Schrodinger's Cat paradox. I shall review the line
of argument which leads to the paradox in the next section; for present
purposes it is sufficient to recall that it essentially consists in the conclusion
that a macroscopic object (in the original version, a cat) may be in a linear
superposition of states corresponding to macroscopically different behaviour,
provided only that it is not "observed". Once an observation or "measurement" is made, however, the system immediately collapses into a state with
definite macroscopic properties. Now whatever one's reaction to the paradox,
it is clear (cf. next section) that it only arises at all because one has implicitly
assumed that the linear laws of quantum mechanics, in particular the superposition principle, apply to the description of any physical system, even when it is
of macroscopic dimensions and complexity. The question then arises whether
there is any experimental evidence for this assumption: In particular, is there
actually any evidence that macroscopic systems can under appropriate conditions
be in quantum states which are linear superpositions of states with different
macroscopic properties? That is the question to which this paper is devoted.
The plan of the paper is as follows. In the next section I briefly review
the Schrodinger's Cat paradox, paying particular attention to the implicit
assumptions involved in its formulation.

Intro to PRL: "The observation of macroscopic quantum tunneling
is regarded as a test of whether quantum mechanics is
valid for macroscopic variables, a fundamental question that has only recently been addressed experimentally."

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Dan Garisto @dangaristo.bsky.social · 1d

Nobel coverage is fast-paced, and there's often not time to reflect on the accomplishment before the next one. (Congrats to the Chem laureates, by the way.)

My day two story on why Clarke, Devoret, and Martinis were looking for macroscopic quantum tunneling and how they managed the tricky search:

Quantum Tunneling Is a Big Deal. This Year's Nobel Physics Prize Shows Why

The Nobel Prize in Physics for 2025 honors scaled-up quantum physics—while sidestepping controversies swirling around quantum computing

www.scientificamerican.com

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Dan Garisto @dangaristo.bsky.social · 1d

Devoret designed transmons; Martinis has done groundbreaking work with quantum computers.

The point is that Nobel Committee could easily have cited quantum computing for this prize. That they did not and kept it in the background is notable.

Dan Garisto @dangaristo.bsky.social · 2d

Suspect we'll see more of this, given the funding situation.

Meg Schwamb @megschwamb.bsky.social · 2d

Sad to see the University of Washington Astronomy Department has suspended graduate admissions for the 2026-2027 Academic Year. astro.washington.edu/graduate-adm...

Graduate Admissions | Department of Astronomy | University of Washington

The Department of Astronomy has suspended graduate admissions for the 2026-2027 Academic Year. General Information for applying to UW Astronomy Graduate Program. Applications must be submitted using ...

astro.washington.edu

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Dan Garisto @dangaristo.bsky.social · 2d

hmm, not what I'm seeing on the website

BBC headline: "Physics Nobel prize awarded to three quantum physicists"

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Dan Garisto @dangaristo.bsky.social · 2d

Yes, but even then it's amid discussion of other applications for superconducting circuits. If the Committee wanted to highlight QC it with this prize they could have done so. That they went out of their way to avoid it is notable.

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Dan Garisto @dangaristo.bsky.social · 2d

QC is not ready for primetime. This is an interesting discovery on its own merits, with applications beyond QC, though QC is heavily implicated.

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Dan Garisto @dangaristo.bsky.social · 2d

It's a very careful prize. Celebrates 100th anniversary of QM without really supporting QC, though it is there in the wings.

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Dan Garisto @dangaristo.bsky.social · 2d

You are on this council meme but we do not grant you the rank of master, but with quantum computing

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Dan Garisto @dangaristo.bsky.social · 2d

Interesting bit of sociology: They are really studiously avoiding any mention of quantum computing. First and only mention came in the last few words of the presentation by Johansson.

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Dan Garisto @dangaristo.bsky.social · 2d

In many ways, Nobel day is like SantaCon. www.youtube.com/watch?v=m9FU...

A screenshot of the live chat on Youtube.

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Dan Garisto @dangaristo.bsky.social · 3d

Missed some days last week, but I'll try to be consistent this week.

Dan Garisto @dangaristo.bsky.social · Sep 8

I've complained a couple times about the lack of physics community here but not done much about it! New commitment: I'll post one interesting arXiv paper a day until things are better.

(To the folks who follow me for non-physics science policy, don't worry; plenty more of that reporting to come.)

Dan Garisto @dangaristo.bsky.social · 3d

Day 16

Dan Garisto @dangaristo.bsky.social · 3d

Two neat planetary searches for dark matter that annihilates/decays:

1. Annihilation into photons would melt earth's core and heat it up. arxiv.org/abs/2505.24070
2. Annihilation into electrons excites hydrogen molecules, which then illuminate the atmosphere of gas giants.
arxiv.org/abs/2408.15318

Figure 1. A planet with aurorae (at the poles, magenta), and
a dark matter induced ultraviolet airglow (isotropic, green).

Dan Garisto @dangaristo.bsky.social · 3d

(This is not to endorse either as a place where DM is likely to be found, but the papers as a creative and reasonable exploration of parameter space, with accessible observables. Would be quite the thing if UV radiation data from Voyager 1's pass of the outer planets contributed to DM detection.)

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Dan Garisto @dangaristo.bsky.social · 3d

Limits from airglow in gas giants are quite a bit better than heating the core (first order intuition: larger detector gives better results?).

FIG. 6. Our limit from the existence of a solid inner core
is shown in red. We also show other limits from Earth
heating (teal and blue) [41, 43, 61], star formation and stellar disruption (purple and burgundy, respectively) [50], and
airglow in gas giant atmospheres (dashed black and dashed
gray) [47, 48]

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Dan Garisto @dangaristo.bsky.social · 3d

Two neat planetary searches for dark matter that annihilates/decays:

1. Annihilation into photons would melt earth's core and heat it up. arxiv.org/abs/2505.24070
2. Annihilation into electrons excites hydrogen molecules, which then illuminate the atmosphere of gas giants.
arxiv.org/abs/2408.15318

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Dan Garisto @dangaristo.bsky.social · 4d

Atomic energy. Maybe not messianic, specifically, but prophetic/apocalyptic--and far more justified to be so.

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Dan Garisto @dangaristo.bsky.social · 5d

The Times provides an explanation for why Trump claimed a deal with Harvard was at hand: a phone call where no deal was made. www.nytimes.com/2025/10/03/u...

Mr. Schwarzman began the effort in early September. A pivotal conversation took place on Tuesday, when Mr. Schwarzman called Mr. Trump at the White House while on a trip to London, where he had traveled, in part, for a dinner with Prince William, the heir to the British throne.

While on the call, Mr. Schwarzman was placed on speakerphone in the Oval Office, and was drawn into a heated argument over the terms of the deal with Ms. Dhillon, who was in the room along with Ms. MacMahon, Attorney General Pam Bondi and Stephen Miller, the White House deputy chief of staff, among others, according to three people briefed on the discussion.

Mr. Trump appeared delighted by the back-and-forth and laughed it off, the people said.

Despite the argument, the ploy to reach Mr. Trump worked, as almost immediately after speaking with Mr. Schwarzman, Mr. Trump announced publicly that a deal was close but said the final terms had to be ironed out.

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Dan Garisto @dangaristo.bsky.social · 6d

Searing editorial from the EIC of The Lancet: "Those I can’t forgive are Bhattacharya and Makary, both physicians with experience of what constitutes evidence for causal explanations of disease. ... They both know that evidence linking vaccines to autism simply does not exist. What are they doing?"

Offline: Those one should not forgive

What was even more shocking than a US President telling pregnant women, “Don’t take Tylenol [paracetamol, acetaminophen], don’t take it…fight like hell not to take it”, was watching the Director of th...

www.thelancet.com

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