Quantum computers have the potential to completely revolutionize information technology as we know it, and a new breakthrough might have taken a significant step closer towards them.
An international research team was able to flip the spin of electrons from an excited state to a relaxed state using microwaves. By returning to their releaxed (or ground) state, the electrons also released some energy as a microwave photon. The findings, published in Nature, could have important implications for quantum computers.
Elementary particles have an intrinsic property called spin. The math that describes this property makes it seem like the particle rotates on itself, hence the name. If an electron’s spin is excited and left on its own, it takes about 10,000 years for it to naturally decay back to the ground state. This is known as the Purcell effect. But the team was able to force this decay on command.
What has been achieved in this research is equivalent to the wiring of a quantum computer. In normal computers, information is stored as individual bits that can be either a zero or one, while in quantum computing the quantum bits (qubits) can be a zero, a one, and a zero and one at the same time. Electron spins are ideal candidates for qubits, and this new study indicates that the information can be moved from the electrons using photons. A large system of photon-electron links would allow for faster and more powerful computations.
The team had a small sample of highly purified silicon, in which was implanted a matrix of bismuth atoms and a superconducting aluminum circuit. The electrons in the bismuth atoms were then “flipped” into the excited state. The aluminum circuit was used by the scientists to tune the microwave and force the electrons to flip back to the ground state.
“Our results are highly significant for quantum information processing,” Patrice Bertet, a quantum electronics scientist at the French Atomic Energy Commission (CEA) who led the experiment, said in a statement. “Indeed, they are a first step toward the strong coupling of individual electron spins to microwave photons, which could form the basis of a new spin-based quantum computer architecture.”