"Attoclock" measures electrons moving at quintillionths of a second
Movements at the particle scale happen extremely quickly, which can make it hard to see what’s going on in there. Now, engineers at the Universities of Michigan and Regensburg have developed an “attoclock” that can take snapshots of electrons in increments as small as quintillionths of a second.
For current computers, clock speeds are measured in nanoseconds, which are a billionth of a second. And while that’s fast enough for what we use them for today, quantum computers have the potential to drastically speed things up – we just need the right tools first.
“Your current computer’s processor operates in gigahertz, that’s one billionth of a second per operation,” said Mackillo Kira, lead author of the study. “In quantum computing, that’s extremely slow because electrons within a computer chip collide trillions of times a second and each collision terminates the quantum computing cycle. What we’ve needed, in order to push performance forward, are snapshots of that electron movement that are a billion times faster. And now we have it.”
The team’s new device takes measurements on a completely different timescale – attoseconds, which are one quintillionth of a second. To hammer home how short that timeframe is, there are more than twice as many attoseconds in one second as there are seconds in the entire history of the universe to this point.
It goes without saying that recording time increments this tiny would be challenging, but the team has developed a new system that lets them do so. The technique involves two light pulses with energies that match the electrons – the first is a pulse of infrared light that gets the electrons into a state where they can move through a semiconductor material. Next, a lower-energy terahertz (THz) pulse is applied, which sends the electrons onto trajectories to force head-on collisions. This produces a flash of light, and the precise timing of these flashes can be analyzed to reveal quantum interactions and other details.
“We used two pulses – one that is energetically matched with the state of the electron, and then a second pulse that causes the state to change,” said Kira. “We can essentially film how these two pulses change the electron’s quantum state and then express that as a function of time.”
The team says that devices like this are a first step towards better quantum computers by advancing our understanding of how electrons move, behave and interact in materials.
The research was published in the journal Nature.
Source: University of Michigan