Entanglement is of central importance for the new quantum technologies of the 21st century. A research team has now realized controlled multi-particle entanglement in a system of 20 quantum bits, which is the largest entangled quantum register of individually controllable systems to date.
"We generate and characterize entangled states of a register of 20 individually controlled qubits, where each qubit is encoded into the electronic state of a trapped atomic ion," said the research team, led by Ben Lanyon and Rainer Blatt at the Institute of Quantum Optics and Quantum Information (IQOQI) of the Austrian Academy of Sciences, together with theorists from the University of Ulm and the Institute of Quantum Optics and Quantum Information in Vienna.
According to the new study, published in the current issue of Physical Review X, the research team was able to detect genuine multi-particle entanglement between all neighbouring groups of three, four and five quantum bits.
Physicists all over the world are working on implementing entangled systems with more and more quantum bits.
"The particles are first entangled in pairs," Lanyon was quoted as saying in a news release. "With the methods developed by our colleagues in Vienna and Ulm, we can then prove the further spread of the entanglement to all neighbouring particle triplets, most quadruplets and a few quintuplets."
Researchers hope to further increase the number of quantum bits in the experiment.
"Our medium-term goal is 50 particles," said Blatt. "This could help us solve problems that the best supercomputers today still fail to accomplish."
However, there are a lot of things beyond qubit count that must be taken into consideration.
Other researchers have announced computers using a similar technology with 51 or 53 qubits.
Last month, Google took a step forward in its bid to become the first company to demonstrate "quantum supremacy" with its newest 72-qubit quantum processor.
In January, Intel announced its own 49-qubit quantum chip. Last November, IBM announced that it was testing a prototype quantum processor with 50 qubits.
"So the community is marching forward, building more and more sophisticated systems for which the evidence of quantum supremacy will become more and more sound," Patrick Hayden, a physicist and computer scientist at Stanford University told Xinhua in an email.
"Quantum error correction will be a crucial feature of a full-strength quantum computing system and showing that it can work in practise is as exciting to me as quantum supremacy!"
