Quantum machine facts for kids
A quantum machine is a special device built by people. Its tiny parts move according to the rules of quantum mechanics. These rules are usually seen only in very small things, like atoms. For a long time, scientists thought it was impossible to see quantum rules in bigger objects. This is like the idea of Schrödinger's cat, where a cat could be both alive and dead at the same time.
It's hard to see quantum effects in large objects. This is because these effects are very delicate. They easily disappear due to something called quantum decoherence. This means outside influences can quickly mess up the quantum state. Scientists first created a working quantum machine in 2009. This amazing achievement was called the "Breakthrough of the Year" by Science magazine in 2010.
How Scientists Built the First Quantum Machine
The first quantum machine was built on August 4, 2009. It was created by Aaron D. O'Connell and his team. They worked at the University of California, Santa Barbara. The team included Andrew N. Cleland and John M. Martinis.
They connected two main parts. One was a mechanical resonator, like a tiny springboard. The other was a qubit. A qubit is a special device used in quantum computing. It can be in two different states at the same time. This is called a superposition.
The scientists made the tiny springboard vibrate in a special way. It vibrated both a little and a lot at the same time. This is something that cannot happen in normal, everyday physics. The springboard was about as wide as a human hair. You could just barely see it without a microscope.
This important discovery was published in Nature magazine in March 2010. Later that year, Science magazine named it the "Breakthrough of the Year".
Cooling the Machine to Its Lowest Energy
To show quantum behavior, the team had to cool the tiny springboard. They needed to cool it until it reached its quantum ground state. This is the state where an object has the lowest possible energy.
Other research teams had tried this before. But it was very difficult. For example, a springboard vibrating 1 million times per second would need to be super cold. It would need to be cooled to about -273 degrees Celsius. That's almost as cold as space!
O'Connell's team used a different kind of springboard. It was called a "film bulk acoustic resonator." This resonator vibrated much faster, about 6 billion times per second. Because it vibrated so fast, it didn't need to be quite as cold to reach its ground state. It only needed to be cooled to about -273 degrees Celsius. This temperature could be reached using a special fridge called a dilution refrigerator. In their experiment, the team cooled the springboard to an even colder temperature.
How Scientists Controlled the Quantum State
The special springboard was made from a piezoelectric material. This means its shape changes when electricity is applied. And when its shape changes, it creates an electric signal. This property allowed the springboard to be connected to a superconducting phase qubit. This qubit is a device used in quantum computing. Scientists can control its quantum state very precisely.
In quantum mechanics, vibrations are made of tiny energy packets called phonons. When the springboard was cooled to its ground state, it meant all the phonons were removed. The team then found a way to move individual phonons from the qubit to the springboard.
They also managed to transfer a superposition state. This means the qubit was in two states at once. When this state was moved to the springboard, the springboard "literally vibrated a little and a lot at the same time." This was a huge step for science. These special vibrations only lasted a few nanoseconds. That's a tiny fraction of a second. Outside influences quickly broke them down.
In their research paper, the team wrote something important. They said their work showed that quantum mechanics applies to objects big enough to see.
