A laptop just solved a problem that was supposedly impossible without a quantum computer

[EthanHinds]

Physicists at the Simons Foundation's Flatiron Institute, working with collaborators at Boston University, used tensor networks to compress the wave function created by hundreds of entangled qubits, and got the whole calculation running on an ordinary laptop. Lead author Joseph Tindall describes the technique as essentially a zip file for the wave function, squeezing down a mathematical object that would normally be far too large to handle classically. The results matched both theoretical predictions and simulations run on an actual quantum computer

This directly challenges an earlier claim from a team led by Andrew D King and collaborators, who had published a paper arguing their quantum computer's results on this exact class of problem were beyond the reach of any classical machine. Tindall's team says they were skeptical of that beyond classical framing from the start and set out to test it using an adapted version of an algorithm originally developed back in the 1980s

The specific problem involved simulating quantum systems built from hundreds of interacting qubits arranged in square, cubic and diamond lattices, the kind of setup where qubits exist in superposition rather than simple 0 or 1 states. Getting a laptop to match that using pure mathematics and the team's ITensor software library, rather than any quantum hardware at all, is being described as a real challenge to how casually the beyond classical label gets applied in this field going forward

An ordinary laptop solved a problem thought to require a quantum computerwww.sciencedaily.com

[Di46]

Tindall calling it a zip file for the wave function is such a clean way to describe what tensor network compression is actually doing

[Nebula Diane]

This is the kind of result that should make every quantum supremacy headline get read a little more skeptically from now on

[Anchor34]

Using a 1980s algorithm to undercut a 2026 quantum hardware claim is a wonderful piece of scientific irony

[Amber84]

Curious how D-Wave's team is responding to having their beyond classical claim directly challenged like this

[Craig71]

This does not mean quantum computers are useless, it just means the bar for beyond classical claims needs to be a lot higher

[Neil57]

ITensor keeps quietly being one of the most useful pieces of open software in this whole field

[Scholes]

Would love to see a head to head timing comparison, laptop versus the actual quantum hardware on the exact same problem

[Mesh Gareth]

Skepticism from the CCQ team on beyond classical claims seems to be a running theme, they keep finding classical workarounds

[AEWNoah32]

This is a good reminder that qubit count alone tells you very little about whether a problem needs quantum hardware

[DelPiero58]

Great example of why replication and independent verification matter so much in a field this hyped