ABC Science claims that this might include objects as large as the width of a human hair. This massive quantum entanglement experiment could help solve a physics mystery
Written by science reporter Belinda Smith on 26 April 2018.*
I quote Smith’s words as follows.
Quote:
“Physicists
detected signs of entanglement between two vibrating ‘drumheads’,
each around the width of a human hair.
Few
ideas are as mind-bending as quantum entanglement: that two objects
remain intimately intertwined, even if they’re at opposite ends of
the universe.
Key
points:
- Particles
are entangled if they are created at precisely the same time and
point
- Entangling
massive objects in a stable way has proved tricky for experimental
physicists
- In
a paper published this week, two vibrating ‘drumheads’, comprising
trillions of atoms, were kept in an entangled state for 30 minutes
- Observing
quantum states in massive objects could help reconcile quantum
mechanics with Einstein’s theory of general relativity
To
date, stable entangled objects created by scientists have been mostly
limited to tiny particles. Think atoms or electrons.
But
a team of physicists has for the first time kept two vibrating metal
membranes, each made of trillions of atoms, entangled for a good half
hour, according to a study published in Nature.
The
membranes may seem infinitesimal to us, at around the width of the
finest human hair, but they were massive on an atomic scale.
These
kinds of experiments could help physicists reconcile two seemingly
incompatible concepts in science — general relativity and quantum
mechanics — said Matt Woolley, a physicist at the University of New
South Wales Canberra and one of the report’s authors.
Get
acquainted with entanglement
Particles
are entangled if they are created at precisely the same time and
point.
It’s
reasonably straightforward to do in the lab, said Ben Buchler, a
physicist at the Australian National University who was not involved
in the study, and physicists can control their properties.
In
his own research, for instance, he can split a photon — a tiny
packet of energy that makes up light — into two.
These
“offspring” each have half the energy of the original
photon, but are entangled.
Imagine
we have a couple of photons entangled in a way that means if one
photon vibrates in a specific direction — say, up and down — the
other will always vibrate side to side.
If
you measure the vibration state of one entangled photon, you’ll
immediately know the state of its twin, regardless of the distance
between them.
Quantum
particles can affect one another’s behaviour over vast distances.
But
Dr Woolley wasn’t interested in anything as ephemeral as a photon.
He
and his colleagues from Finland and the United States went big.
They
made a pair of vibrating aluminium membranes, or “drumheads”,
each 20 microns across.
“You
can’t quite see them with the naked eye, but they’re pretty close,”
Dr Woolley said.
These
were connected to metal plates via a superconducting electrical
circuit, which had no electrical resistance.
The
whole shebang was cooled to a touch above absolute zero, or -273
degrees Celsius.
Microwaves
coursing through the circuit entangled the drumheads. And the
drumheads stayed entangled for 30 minutes.
Quantum
mechanics: it’s all relative
These
days, entanglement is accepted as a lynchpin of quantum mechanics,
but it wasn’t always the case.
It
takes more than entanglement to impress Albert Einstein.
Einstein
wasn’t convinced by the idea, famously calling the concept “spooky
action at a distance”.
But
it’s this spooky action, which bestows absolute and immediate
certainty about the properties of something next door or even half a
world away, that forms a fundamental part of quantum communication.
There’s
also teleportation — not in the science fiction sense of beaming
matter from one place to another, but reproducing the quantum state
of entangled objects, Dr Woolley said.
The
drumhead experiment might also be used to find a way to reconcile
quantum mechanics with Einstein’s theory of general relativity, which
describes gravity as curved space-time, Dr Buchler said.
“We
know, at least from a mathematical perspective, that general
relativity is inconsistent with quantum mechanics,” he said.
“Everything
we see in the sky seems to agree brilliantly with general relativity
and everything we see that’s very small works brilliantly with
quantum mechanics.
“And
yet we know one or both of these theories are incomplete in some way,
because we can’t stick them together mathematically.”
The
real challenge, he added, is to design and carry out more experiments
where general relativity and quantum mechanics are important at the
same time — something that he believes might be plausible in the
next decade.
Physicists
might just then unravel the physics that dominated the first moments
of the universe.
“At
the very early universe, you had a very tiny object which exploded,
and the entire universe was created,” Dr Buchler said.
“When it was very small, quantum mechanics must have been important. As it became larger, we describe it with general relativity.””
*If the words in this presentation seem to you to have a degree of validity I introduce you to this David Bohm documentary trailer to the full Infinite Potential video. In doing this try to understand the philosophical commentary thereto rather than the physics debate therein. Some of the science is complicated and not designed to be fully understood by lay persons, including me.