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Shanxi University team reports measurements beyond the Heisenberg limit

Shanxi University team reports measurements beyond the Heisenberg limit

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A 52-billion-atom rubidium experiment combined past and future readings to estimate position and momentum at once, about 20% more precisely than the standard bound. The paper is an unreviewed preprint.

Today: Shanxi team reports measuring both at once

Overview

Updated 1 hour ago

Werner Heisenberg's 1927 rule says you cannot pin down a quantum particle's position and its momentum at the same time. A team at Shanxi University in China reports it did both, estimating the pair about 20% more precisely than the uncertainty limit allows by folding in measurement data from before and after the moment in question.

The work is an arXiv preprint that has not been peer-reviewed, and it does not repeal the uncertainty principle. If it survives scrutiny, the same trick could quiet the readouts in atomic clocks, gravitational-wave detectors and navigation systems, where quantum noise sets the floor on precision.

Why it matters

If it holds up, sharper quantum sensing could improve atomic clocks, gravitational-wave detectors and navigation systems that live or die on noise.

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Key Indicators

20%
Precision gain over the Heisenberg limit
The authors report estimating position and momentum about 20% more precisely than the standard bound allows.
52 billion
Rubidium atoms in the test chamber
A laser aligned their spins so the atoms behaved as one quantum system.
84 min
Continuous measurement window
The experiment collected readings without a break for 84 minutes.

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People Involved

J. Li
J. Li
Lead author of the Shanxi University preprint
Preprint posted to arXiv; not peer-reviewed
KM
Kater Murch
Physicist, Washington University in St. Louis
Led the 2015 retrodiction experiment

Organizations Involved

Shanxi University
Shanxi University
University
Led the 2026 rubidium-atom experiment

University in Taiyuan, China, whose research team led the experiment reported in the November 2026 preprint.
WU
Washington University in St. Louis
University
Hosted the 2015 hindsight-prediction experiment

St. Louis university whose physics lab produced the 2015 demonstration that future data can sharpen a past quantum state estimate.
arXiv
arXiv
Preprint server
Hosts the unreviewed paper

Preprint repository where the Shanxi University paper is posted before peer review.

Timeline

1927 November 2026

4 events Latest: Today
Tap a bar to jump to that date

  1. Shanxi team reports measuring both at once

    Today Preprint

    A 52-billion-atom rubidium experiment combined past and future readings, reporting 20% better precision than allowed.

  2. Yale catches a quantum jump early

    Experiment

    Continuous monitoring of a superconducting qubit revealed a warning sign ahead of a quantum jump.

  3. Hindsight beats the forward guess

    Experiment

    Murch lab combined past and future data; hidden-state guesses rose from 50-50 to 90-10.

  4. Heisenberg sets a limit on knowing

    Theory

    Heisenberg's uncertainty principle: precise knowledge of one variable blurs its paired variable.

Scenarios

1

Peer review upholds the 20% gain

Possible Resolves by Nov 12, 2027

Discussed by: The Shanxi University authors, whose preprint is posted to arXiv pending review

The paper clears review at a journal without the central precision claim being revised downward. That would move the result from a preprint assertion to an accepted measurement technique, and would make the two-way readout a candidate method for quantum sensors.

2

Independent lab fails to reproduce the gain

Possible Resolves by Q2 2028

Discussed by: No group has announced a replication attempt as of November 2026

Another lab runs the same hindsight protocol on cold atoms or superconducting qubits and finds the precision advantage shrinks or vanishes once systematic errors are counted. That would leave the practical ceiling on simultaneous estimation where it was.

3

Quantum sensor labs adopt hindsight estimation

Unlikely Resolves by End of 2029

Discussed by: The preprint authors, who point to quantum-enhanced sensing as the payoff

An atomic-clock, magnetometer or gravitational-wave group builds the two-way readout into a working instrument and reports a measurable sensitivity improvement. At that point the physics question becomes an engineering problem, and the technique's limitation, that it needs data from after the moment being measured, starts to matter in practice.

Historical Context

3 moments from history that rhyme with this story — and how they unfolded.

1927

Heisenberg's uncertainty principle (1927)

Werner Heisenberg described a trade-off in knowing paired quantum variables. Pin down a particle's position and its momentum becomes less certain, and the reverse holds too.

Then

Physicists treated the limit as a fact of nature rather than a flaw in instruments.

Now

It set the noise floor for atomic clocks, interferometers and any device that reads quantum signals.

Why this matters now

The Shanxi team says its result does not repeal the principle, only works around the estimation limit it imposes.

February 2015

Hindsight prediction in a superconducting qubit (2015)

Kater Murch's lab at Washington University in St. Louis hid the result of a strong measurement on a qubit, then tracked it with weak measurements. Combining forward and backward calculations raised the odds of guessing the hidden state from 50-50 to 90-10.

Then

The Physical Review Letters paper argued that data from after a measurement can sharpen claims about a quantum state before it.

Now

It established retrodiction as a laboratory technique and a recurring argument about time symmetry in quantum mechanics.

Why this matters now

The 2026 experiment applies the same past-plus-future logic to continuous position and momentum rather than a two-state qubit.

June 2019

Predicting a quantum jump at Yale (2019)

Yale researchers monitored a superconducting qubit continuously and saw a telltale absence of photons just before it jumped between states. The signal came early enough to act on.

Then

The team showed a quantum jump can be caught in progress, not only logged afterward.

Now

Continuous weak readout became a standard tool in qubit experiments.

Why this matters now

Hindsight estimation depends on the same kind of gentle, uninterrupted readout.

Sources

(3)
ScienceAlert ScienceDaily / Washington University in St. Louis Yale News