Acoustic manipulation of electron spins can improve quantum control
Recently, German and Russian scientists have jointly developed a method for acoustic manipulation of spin qubits, demonstrating the interaction between the strain field of surface acoustic waves and the excited state spin of silicon vacancies in silicon carbide. The new method is expected to improve the quantum control of electron spin and provide new possibilities for miniature quantum devices to efficiently process quantum information.
Color centers are lattice defects in crystals that can trap one or more additional electrons. The trapped electrons usually absorb light in the visible spectrum, so transparent materials (such as diamonds) will be colored through these centers. Color centers are usually related to certain magnetism, which makes them very promising in quantum technology applications, such as quantum memory or quantum sensors. The scientific challenge is to develop effective methods to control the magnetic quantum properties of electrons or control their spin state. In recent years, the spin manipulation of the silicon carbide color center has become an emerging research direction.
Recently, the joint research team of the Paul Druder Institute of Solid State Electronics in Germany, the Helmholtz Dresden Rosendorf Research Center, and the Effie Institute of Physics and Technology of the Russian Academy of Sciences published a paper in the journal "Science Progress", showing The huge interaction between the strain field of the surface acoustic wave and the excited state spin of the silicon-vacancy in the silicon carbide. This coherent acoustic manipulation of ground and excited state spins provides new opportunities for efficient quantum information protocols and coherent sensing.
Dr. Alexander Poshajinsky from the Effie Institute of Physics and Technology said: “People can think of this control as tuning a guitar with an ordinary electronic tuner. It’s just that our experiment is a little more complicated: The resonance frequency of the spin is adjusted to the frequency of the sound wave, and the laser excites the color center to transition between the ground state and the excited state."
Dr. Alberto Hernandez-Minges of the Paul Drude Institute explained: “When a gyroscope moves, precession is a change in the direction of the axis of rotation. We can think of electron spin as a miniature gyroscope. In this way, the precession axis is affected by the sound wave, and each time the color center transitions between the ground state and the excited state, it will change its direction. Since the color center is in the excited state for a random length of time, the progress of the ground state and the excited state The huge difference in the orientation of the moving axis means that the orientation of the electron spin and the quantum information stored in it change in an uncontrolled manner. "This change causes the quantum information stored in the electron spin to be lost after multiple transitions.
In order to prevent this from happening, the joint research team developed a new method: by appropriately adjusting the resonant frequency of the color center, the precession axis of the spin is collinear in the ground state and the excited state. That is, the spins maintain their precession direction in a well-defined direction, even if they jump back and forth between the ground state and the excited state. Under this special condition, the quantum information stored in the electron spin is decoupled from the jump between the ground state and the excited state caused by the laser. This acoustic manipulation technology provides new possibilities for processing quantum information in a quantum device similar in size to a microchip. It may also have a huge impact on production costs, thereby promoting the availability of quantum technology for the masses.
