Creating qubits that can move

Like any other chip that is made, the wires that connect the quantum dots are sealed at the point where the chip is made. Since different error-correction methods require different connections between qubits, this forces us to commit to error-correction features during design. If a good scheme is created after the chip is made, it may not be possible to change it. Small-scale algorithms can benefit from simple error-correction methods that require minimal programming, but we cannot change configurations and chips.

Therefore, the increasing number of dots seems to represent the trade-off we are facing with quantum computing: it is easy for us to create more dots with all the tools necessary to use them, but it seems impossible for them to benefit from the flexibility that other types of qubits have.

The whole point of this new paper is to show that this is not true.

Moveable dots

The new project was carried out in collaboration between Delft University of Technology researchers and the founders of QuTech. The team created a chip that contained a series of rows of quantum dots, and they started with electron spins at each end. Then, using the appropriate electrical signals, they can transfer the spins into the net drop, gradually bringing them closer together. (And, by slow, we mean a fraction of a second here, but slow compared to an electrical switch.)

When the electrons got close enough, the spin wavefunctions overlapped, allowing the researchers to create two qubit gates on them. These variables can be used to block the two spins and thus require the creation of error corrections; These gates also need to do math.

The researchers proved that they could move the electrons back to where they started, and then measurements confirmed that their spins were aligned. And since quantum teleportation also requires a qubit-qubit gate, he showed that this technique could be used for teleportation. Teleportation can improve the mobility provided by moving qubits around, as it can be used to move the states of the qubits further apart.