CMS researchers observe quantum entanglement in prime quark–antiquark pairs, revealing new insights into quantum behaviour on the smallest scales
Quantum entanglement is an enchanting phenomenon wherein the states of two particles turn out to be intrinsically linked, such {that a} change in a single particle’s state immediately impacts the opposite, whatever the distance between them. This nonlocal connection results in outstanding results, together with the power to affect one particle by manipulating its entangled accomplice. Famously, Einstein referred to quantum entanglement as “Spooky Motion at a Distance”. Till now, entanglement has been noticed in programs involving atoms, electrons, and photons.
Researchers from the CMS Collaboration at CERN have used information collected in 2016 on the Massive Hadron Collider (LHC) to research quantum entanglement in prime quark–antiquark pairs. In these experiments, protons had been collided at extraordinarily excessive energies (13 TeV), which, as predicted by Quantum Chromodynamics, can result in the manufacturing of prime quark pairs. The highest quark is the heaviest recognized elementary particle, and each it and its antiquark counterpart decay virtually immediately after being produced.
On this research, CMS centered on occasions the place two leptons (equivalent to electrons or muons) had been detected with reverse fees and excessive momentum. These leptons originate from the decay of the highest quark and antiquark and carry details about their father or mother particles, together with their spin. To probe entanglement, the researchers used an observable known as D, which quantifies the correlation between the spins of the highest quark and antiquark. A worth of D < -1/3 serves as a transparent signature of quantum entanglement. The CMS outcome lies greater than 5 normal deviations beneath this threshold, establishing the remark of entanglement in prime quark-antiquark pairs. This affords invaluable perception into the behaviour of quantum programs underneath excessive vitality circumstances.
The ATLAS Collaboration beforehand reported the primary remark of entanglement. This measurement was carried out on the degree of steady particles, reconstructed after hadronization. In distinction, the CMS measurement was carried out on the parton degree, which refers back to the behaviour of the unique constructing blocks of particles (quarks and gluons) earlier than they type composite particles. This strategy offers a complementary view of the quantum state.
This groundbreaking work not solely confirms that quantum mechanics holds true on the highest energies and shortest timescales by revealing entanglement within the manufacturing of the heaviest elementary particles, but additionally establishes particle colliders just like the LHC as highly effective platforms for exploring quantum data science.
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High quark physics in hadron collisions by Wolfgang Wagner (2005)
