(August 18, 2015) Per
Delsing and his team want to combine theoretical calculations with experiments
on superconducting circuits to gain an understanding of how things fit together
at the nano level. Among other things, they plan to simulate objects that move
very rapidly, almost at the speed of light, and demonstrate the “twin paradox”
on a microchip.
Stuck on the wall of Per’s office is a piece of paper on
which is written: “It is easier to control a photon than it is to bring up four
daughters.”
“That’s right,” says Per, who is Professor of Experimental
Physics at Chalmers University of Technology, without a second’s hesitation.
But then again, he is a wiz at controlling photons – small
particles of light. Among other things, his research team has succeeded in
generating photons directly out of a vacuum. In their project, which has
received funding from the Knut and Alice Wallenberg Foundation, they are using
photons to demonstrate the twin paradox in a new way. The paradox is a thought
experiment stemming from Einstein’s special theory of relativity, and has
occupied the minds of physicists for more than a hundred years.
Per, who happens to be a twin himself, explains:
“The twin paradox says that if I take a space journey in a
high-speed rocket and then return, as an effect of acceleration I will be much
younger than my twin brother. This effect has been measured in various ways.
What we want to do now is to demonstrate this on a microchip.”
In other words, instead of traveling into space, his
research team will move photons a very short distance at nano level.
“But the photons travel so quickly, close to the speed of
light, which is difficult for us to reach in reality. And this is why we can
achieve an effect even though this space journey only takes place on the actual
chip.”
The trick – a
superconducting circuit
The team is using a special type of superconducting electric
circuit called SQUID, which stands for Superconducting Quantum Interference
Device, which has been made in Chalmers’ advanced clean room. When Per’s team
showed in 2011 how to create photons out of a vacuum, they used the specially
designed SQUIDs as ultra-high-speed mirrors to generate light particles.
In addition to the twin paradox, the project aims to study
two other new physical phenomena on microchips: “photon condensation” and
“frequency combs”.
“We always work on the boundaries of what is possible and
what is new. The grant will enable us to realize these ideas and see how far we
can go. The Foundation has also given us great freedom to use the resources as
we ourselves see fit.”