When performing calculations in a quantum computer qubits are required. Qubits are the units that enable the computer to perform calculations.
Qubits are produced in many different ways. Some use an atom or an electron, others utilise photons (light particles), and then there are those that create quantum bits using, for example, electricity and a special composition of materials.
"The ideal quantum bit is a quantum mechanical system over which we have 100% control. This means that we can control its state, and when we place it in a state, it does not change on its own. In addition, it must be possible to measure its state after a calculation with great precision, otherwise it would not be possible to obtain an understandable result from the quantum computer," explains Thomas Sand Jespersen.
He is a professor at DTU Energy where he researches quantum materials and develops solutions that ensure that quantum technologies can be connected to our classical electronics outside the quantum computer.
New type of quantum bit in crystals
Thomas Sand Jespersen says that it is still unclear which type of qubit will be the best solution for the quantum computer. In other words, the search for the perfect qubit is still ongoing.
"It's still relevant to look for and investigate qubits in completely new places. This is one of the things we are currently working on in my group together with a consortium of European research groups from Italy, France, Sweden and Poland," says Thomas Sand Jespersen.
Finding new solutions for quantum bits is not easy, says the professor, who explains:
"The function of a qubit will always be a compromise between different conditions. For example, a qubit that is very isolated from its surroundings will be able to maintain its state for a very long time. That is good, but on the other hand, it becomes correspondingly difficult to read the state of an isolated qubit."
The new qubit that DTU researchers are currently investigating has been found in a type of material that belongs to the category of complex oxides.
Complex oxides are crystals that occur naturally and can be extracted from the earth. Today, they are used in jewellery and as crucial building blocks in energy technologies such as batteries and fuel cells.
They can also be grown artificially, which means that you can have your own crystal production. The Functional Oxides section at DTU Energy is one of the world's leading groups in the production of these materials and has extensive facilities for oxide cultivation at the Lyngby Campus.
