Researchers at the Paul Scherrer Institute (PSI) have developed a way to create faster, more accurate quantum bits – qubits. Researchers have demonstrated how they can be activated, obfuscated, used as memory bits, and read. They have now published their concept of a new quantum computer design and supporting calculations in PRX Quantum magazine.

The central elements of a new type of quantum computer are magnetic atoms from the class of so-called rare-earth metals, which are selectively implanted into the crystal lattice of the material. Each of these atoms represents one qubit.

On the way to quantum computers, the initial requirement is to create so-called quantum bits or qubits – bits of memory that, unlike classical bits, can take not only binary values of zero and one, but also any arbitrary combination.

“This enables a completely new kind of computing and data processing, which for specific applications means a huge acceleration in computing power.”

PSI researcher Manuel Grimm.

Physicists describe how logic bits and basic computer operations with them can be implemented in a magnetic solid: qubits will be located on individual atoms from the class of rare earth elements embedded in the crystal lattice of the base material.

Based on the laws of quantum physics, the researchers calculated that the nuclear spin of rare-earth atoms would be suitable for use as a carrier of information, that is, qubits. They also speculate that targeted laser pulses can instantly transmit information to the electrons of an atom and thus activate qubits, making their information visible to surrounding atoms.

Two such activated qubits interact with each other and thus can be “entangled”. Entanglement is a special property of quantum systems of several particles or qubits, which is important for quantum computers: the result of measuring one qubit directly depends on the results of measuring other qubits, and vice versa.

The researchers demonstrate how these qubits can be used to create logic gates, most notably “NOT” gates (CNOT gates). Logic gates are the basic building blocks that classical computers also use to perform computation. If you combine a sufficient number of such CNOT gates, as well as a sufficient number of one-qubit gates, any conceivable computational operation becomes possible. Thus, they form the backbone of quantum computers.

This is not the first time scientists have proposed using quantum logic gates. However, this method of activating and entangling qubits has a decisive advantage over previous comparable proposals: it is at least ten times faster.

Another advantage lies not only in the speed with which a quantum computer based on this concept can perform computations, but above all, it concerns the susceptibility of the system to errors.

Qubits are not very stable. If the entanglement processes are too slow, there is a high probability that some of the qubits will lose their information in the meantime. In fact, PSI researchers have discovered a way to build a quantum computer not only at least ten times faster than comparable systems, but also less prone to errors in the same factor.