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Quantum physics
says that reality doesn't exist in a fixed state. Image:
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Using quantum entangled particles, scientists have managed to overcome the limits of probability to win a theoretical game more times than should be possible..
Nobel
Prize-winning physicist Richard Feynman once famously declared that “nobody
understands quantum mechanics,” although a new experiment involving quantum
entangled particles does at least help to illustrate one of the key principles
of this mystifying branch of physics. Using a trick called quantum pseudo-telepathy,
the exercise confirms that reality does not exist in a fixed state until it is
measured.
The idea that
physical objects can exist in multiple states simultaneously is known as
wave-particle duality and is demonstrated by the famous double slit experiment.
Using this iconic set-up, scientists have established that photons (light
particles) spread out through space like a wave when no one is watching, but
“collapse” to a single fixed point the moment they are observed.
The ability to
pull a concrete reality from the quantum ether in this way raises the
possibility of overcoming the constraints of classical statistics. To
illustrate this point, physicists have designed a number of theoretical games
in which players have a limited probability of winning as long as they are
unable to communicate with one another, but which can be consistently conquered
using quantum pseudo-telepathy.
For example, the
Mermin-Peres Magic Square Game involves two hypothetical players called Alice
and Bob, each of whom must fill in every square in a three-by-three grid with
either a “1” or a “-1”. A referee then randomly selects one of Alice’s rows and
one of Bob’s columns, and if both players have the same number in the
overlapping square then they win.
To prevent Alice
and Bob from fixing the game by agreeing to just write the same number in every
single square, the rules demand that the numbers in each of Alice’s rows
multiply to give 1 while the numbers in Bob’s columns combine to produce -1.
Most importantly of all, the two players are not allowed to talk to one another
during the game.
When such a game
is played in the real world, the two players’ nine-square grids must differ in
at least one square, which means that it is statistically impossible to win
more than eight times in nine rounds. In the quantum realm, however, Alice and
Bob may be able to win every time.
This is because
quantum mechanics eliminates the necessity for each square to contain a fixed
value before the round is played, allowing a “1” or “-1” to emerge only once
the referee has made a selection. The entire grid is therefore completely fluid
until it is observed, and can be reconfigured with each new round.
Even better, each
square in Bob’s grid can be quantum entangled with the corresponding square in
Alice’s grid, so that as soon as a fixed value is observed in one player’s
square, the other player’s square “collapses” into the same value.
Obviously, such a
game can’t be played using paper and ink, but can be demonstrated using quantum
entangled particles. In a new study appearing next week in the journal Physical
Review Letters, scientists explain how they used ultrafast laser pulses to
excite barium borate crystals, generating pairs of “hyperentangled” photons.
More specifically,
the photons were entangled such that the polarization of one was intrinsically
linked to the orbital angular momentum of the other. Using these values as
surrogates for Alice and Bob’s numbers, the researchers simulated 1,075,930
rounds of the Mermin-Peres game, winning 1,009,610 of these.
Though not
perfect, the 93.84 percent win rate does exceed what should be possible
according to classical statistics, thus proving that physical reality is not
fixed and can be manipulated using quantum entanglement.
Reference: Research Paper
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