Entangled Photons Act as One

Scientists are one step closer to etching smaller computer chips, imaging ever-smaller objects, and detecting gravitational waves, thanks to a recent experiment reported in the May 14th issue of Science.  Yaron Silberberg and his “Ultrafast Optics Group” at the Wiezmann Institute of Science were able to put five photons into an entangled state, called a “N00N” state which is a superposition of two other states, one with all N photons taking path A, the other with every photon taking path B, |N,0>+|0,N>.  Thus, while it is uncertain which path any particular photon will take, it is 100% certain that they will all take the same path.  This experiment demonstrates how quantum entanglement, a correlation between distant particles, can exist between many different photons as well.

That such non-local correlations exist was proved by John Bell in 1964, and accounting for the mechanism by which distant particles or photons are correlated remains one of the biggest puzzles in quantum mechanics to this day.  In the literature on causation, most philosophers assume Continue reading “Entangled Photons Act as One”

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Quantum Effects are Getting Observably Bigger

Thought you were big enough to escape quantum superposition?  A recent demonstration by physicist Andrew Cleland and his colleagues at UC Santa Barbara suggests otherwise.  Tiny particles have always been subject to quantum effects, but many physicists were skeptical those effects could be reproduced in larger objects.  In an amazing leap, Cleland and his team succeeded in demonstrating quantum effects in an object with trillions of atoms, beating the previous record (fewer than 100 atoms) by a factor of over a billion!

Quantum mechanical experiments have long revealed that a particle can exist in a state of superposition, a state that seems to allow it to be in two contradictory states at once.  It seems as if a particle can pass simultaneously through two slits, or be in a ground state and an excited state at once, or even take two wildly different paths through an experiment.  There are many different explanations for such odd behavior (see below) but the important thing is that until now, these effects were unimaginably small.

According to a recent article in Nature, Cleland’s experiment Continue reading “Quantum Effects are Getting Observably Bigger”