Scientists at the University of Oxford developed a quantum network using two different atoms, strontium and calcium, and achieved a record entanglement time of 10 seconds. The achievement paves the way for longer entanglement times between atoms, which is critical in developing distributed quantum computing networks.
One of the most promising advances in quantum physics is the development of quantum computing technologies. Quantum computers use quantum bits, or qubits, to store and process information. Unlike classical bits that can either store values of 0 or 1, qubits can store multiple values between 0 and 1 and use them simultaneously for information processing.
Thus, qubits offer an exponential approach to crunching large amounts of data, which could help tackle problems that even the fastest supercomputers of today will take decades to solve. Quantum computers are thus considered the next frontier of computing. However, a crucial component of scalable quantum computing is quantum entanglement.
Why is entanglement important?
Even though a qubit can store multiple values at once, it real utility lies it being connected to multiple other qubits, which allows a large number of correlations to be explored simultaneously. This is possible only when a qubit is entangled with another qubit, i.e., the state of one determines the state of the other, even though they may not be physically connected.
Entanglement also helps build multi-qubit logic gates, allowing qubits to interact more dynamically than standard units, which are naturally more isolated. It also lets quantum computers handle more complex data structures in their computations and solve some of the toughest problems the world has seen.
Most importantly, though, entanglement allows quantum teleportation and different quantum processors to share information without actually sharing qubits. This facilitates the construction of a distributed quantum infrastructure, thereby helping build quantum computation capabilities at scale.
How Oxford research will help
In their experiments, the researchers at Oxford used a strontium atom and a calcium atom and placed each of them at two different locations. While light links strontium atoms, the team used local operations to extend quantum entanglement to calcium atoms as well, creating a shared quantum state involving all four atoms.
The reason the researchers used calcium in this setup is that it is less sensitive to magnetic noise than strontium and can be used to preserve the quantum state for much longer.
“Different types of atoms offer different advantages and disadvantages for quantum applications,” said Dougal Main, a researcher at Oxford, in a press release. “Having more than one type in your quantum computer lets you take the best from each.”
The researchers demonstrated the benefit of using different atoms by maintaining quantum entanglement for 10 seconds as against a few milliseconds attained with the same set of atoms.
“This could help make future quantum networks useful for tasks that need several distant atoms to share and preserve the same quantum state,” said Gabriel Araneda, a researcher at Oxford University who was involved in the work, in a press release.
“That could include quantum computing, more sensitive measurements made across remote locations, and comparisons between different types of atomic clocks.”
The researchers published the findings in the journal Physical Review Letters.