Team’s quantum object is biggest by factor of billions

By | March 19, 2010

Quantum resonator (A Cleland)Researchers have created a “quantum state” in the largest object yet.

Such states, in which an object is effectively in two places at once, have until now only been accomplished with single particles, atoms and molecules.

In this experiment, published in the journal Nature, scientists produced a quantum state in an object billions of times larger than previous tests.

The team says the result could have significant implications in quantum computing.

… “We know perfectly well that things are not in two places at the same time in our everyday experience, but this fundamental theory of physics says that they can be,” he told BBC News.

Now, Professor Cleland and his team have moved that dividing line, using an object just big enough to be seen with the naked eye.

They used a tiny piece of what is known as a piezoelectric material, which expands and contracts when an electrical current is run through it.

A current applied at a certain frequency causes it to expand and contract regularly and, just like a violin string, the material has a frequency at which it is inclined to vibrate.

They connected this resonator to an electric circuit that the team has been developing for three years. This can be tuned to put in just one quantum of electrical energy.

They cooled the whole apparatus down to a thousandth of a degree above absolute zero and confirmed that their resonator was in its quantum ground state.

The researchers designed the system so that they could “pump in” just one quantum of electrical energy at a time and see the oscillator begin to vibrate as it converted that quantum into one quantum of vibrational energy.

As it vibrated, the team showed that the resonator was in one of the slippery superpositions of states, with both one and zero quanta of energy.

Sensors and sensibility

The result is a huge push toward answering the question of whether quantum mechanical effects simply disappear in objects beyond a certain size.

“As far as mechanical objects are concerned, the dividing line was at around 60 atoms,” Professor Cleland said.

“With this experiment, we’ve shown that the dividing line can be pushed up all the way to about a trillion atoms.”

The ability to create these superpositions of states and to read them out using the same circuit that created them would make for a quantum-based memory storage system – the heart of a potential quantum computer. …

via BBC News – Team’s quantum object is biggest by factor of billions.

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