A breakthrough in quantum entanglement nudges the world closer and closer to quantum computing at a practical, affordable level. The work comes from a team of scientists led by Ben Lanyon and Rainer Blatt. They’re working out of the Institute of Quantum Optics and Quantum Information at the Austrian Academy of Sciences.

The team has broken the old ‘entanglement record, creating a system of 20 quantum bits.

**From alphr.com**

Quantum physicists just smashed the entanglement record, paving the way for faster quantum computers |

Scientists in Germany and Austria have just made an enormous breakthrough in the field of quantum computing.

Using a record system of 20 quantum bits, physicists have achieved a new entanglement record: the largest entangled quantum register of individually controllable systems in history.

The team, led by Ben Lanyon and Rainer Blatt at the Institute of Quantum Optics and Quantum Information (IQOQI) at the Austrian Academy of Sciences, enlisted the help of theoretical physicists from the University of Ulm and the Institute of Quantum Optics.

As a collective, the researchers achieved a “controlled multi-particle engagement” in a record system of 20 quantum bits. Neighbouring groups of three, four and five quantum bits were found to be entangled in a way that had not been seen at such levels before.

In particular, scientists used laser light to entangle 20 calcium atoms, a controlled undertaking which took place in an ion trap experiment.

“The particles are first entangled in pairs,” explains Lanyon. “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.”

This is not a wholly new phenomenon. For years, physicists have been toying with entangled systems (the word “toying” here used very loosely). In fact, seven years ago, Blatt’s research group at the Institute of Experimental Physics at the University of Innsbruck successfully entangled 14 individual quantum bits for the first time, achieving the largest genuinely entangled quantum register.

Quantum physicists just smashed the entanglement record, paving the way for faster quantum computers |

Here is an abstract from the team on their breakthrough:

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. Entanglement is generated amongst the qubits during the out-of-equilibrium dynamics of an Ising-type Hamiltonian, engineered via laser fields. Since the qubit-qubit interactions decay with distance, entanglement is generated at early times predominantly between neighboring groups of qubits. We characterize entanglement between these groups by designing and applying witnesses for genuine multipartite entanglement. Our results show that, during the dynamical evolution, all neighboring qubit pairs, triplets, most quadruplets, and some quintuplets simultaneously develop genuine multipartite entanglement. Witnessing genuine multipartite entanglement in larger groups of qubits in our system remains an open challenge.

Here is a brief explanation of what quantum entanglement is:

Quantum entanglementis a physical phenomenon which occurs when pairs or groups of particles are generated or interact in ways such that the quantum state of each particle cannot be described independently of the state of the other(s), even when the particles are separated by a large distance—instead, a quantum state must be described for the system as a whole.Measurements of physical properties such as position, momentum, spin, and polarization, performed on entangled particles are found to be correlated. For example, if a pair of particles is generated in such a way that their total spin is known to be zero, and one particle is found to have clockwise spin on a certain axis, the spin of the other particle, measured on the same axis, will be found to be counterclockwise, as to be expected due to their entanglement. However, this behavior gives rise to paradoxical effects: any measurement of a property of a particle can be seen as acting on that particle (e.g., by collapsing a number of superposed states) and will change the original quantum property by some unknown amount; and in the case of entangled particles, such a measurement will be on the entangled system as a whole. It thus appears that one particle of an entangled pair “knows” what measurement has been performed on the other, and with what outcome, even though there is no known means for such information to be communicated between the particles, which at the time of measurement may be separated by arbitrarily large distances.

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