Re: Is this atom in two universes or one?

From: Fred Chen <>
Date: Wed, 26 Jan 2000 20:30:14 -0800

Another URL for those interested:

I have a feeling it may be argued there is a forced 'direct' observation of a
superposition of two states in this experiment, so there is no clean analogy to
the classical posing of the Schroedinger Cat paradox. And everything can be
considered to be happening in one universe. The observer (in this case, the
experimenters) 'defines' the universe.


> Published: Thursday, January 20, 2000
> Physicists coax atom to be two places at same time
> Physicists say they have managed to nudge atoms back and forth between our
> everyday world and the strange quantum realm where objects can paradoxically
> be in two places at the same time.
> If physicists can further refine their control over this realm, it could
> result in incredibly fast quantum computers able to crack even the toughest
> encryption codes now used by conventional computers.
> Quantum theory holds that objects on the subatomic level can simultaneously
> be in two places or have other
> properties that seem contradictory in the everyday world.
> Scientists have achieved quantum states. But in an experiment reported in
> today's issue of the journal Nature, they were able to move atoms into and
> out of quantum states with more precision than before. That kind of control
> is necessary if scientists are to come up with practical devices that employ
> quantum principles.
> For example, a quantum computer could store information in the quantum
> states of atoms or molecules instead of in silicon chips. But for such a
> computer to work, scientists would have to be able to block the outside
> forces that can cause a quantum state to collapse.
> David Wineland and fellow researchers at the National Institute of Standards
> and Technology in Boulder, Colo., coaxed a beryllium atom in a vacuum to be
> in two places at the same time -- the paradoxical ``Schroedinger's cat''
> state. The researchers then caused the system to collapse by introducing
> contact to the outside world.
> Austrian physicist Erwin Schroedinger proposed the cat paradox in the early
> 20th century. He described the hypothetical situation of a cat in a box with
> vial of cyanide gas capped by a decaying radioactive atom, which would
> release the poison once it decayed. Under quantum theory, the atom could be
> in both states, meaning the cat could be both dead and alive.
> The researchers in Colorado said they were able to keep a beryllium ion in a
> Schroedinger's cat-like state for as long as as 100-millionths of a second.
> To do that, the beryllium atom was cooled to close to absolute zero -- minus
> 459 degrees -- and isolated from all types of radiation, radio waves and
> other energy sources. The researchers then used lasers to force the atom's
> single electron into two states of spin, which forced the atom to be in two
> places at the same time.
Received on Thu Jan 27 2000 - 00:02:16 PST

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