Electron spin plays an important role in high-precision magnetic induction detection and quantum computers. According to a report recently organized by the Physicist Organization Network, scientists from the University of Konstanz in Germany have theoretically studied the possibility of coupling electron spins and carbon nanotube quantum dots. The results show that the mechanical vibration of carbon nanotubes will greatly affect The spin state of the trapped electrons, while the carbon nanotubes themselves are also affected by electron spins. The researchers pointed out that the discovery of this intrinsic strong spin-mechanical coupling is of great significance for the study of magnetic and material nanosensors, quantum computing, and other nano-application devices. The related papers were published in the recently published Physical Review Letters.
Researchers theoretically couple spin orbits to carbon nanotube quantum dots. In the paper, they envisaged suspending a section of carbon nanotubes in a trench, allowing the nanotubes to function as a phonon cavity. Then resonance is induced by an approach to the resonator from the outside through an antenna-like form, which couples the charge and the carbon nanotubes together. The carbon nanotubes vibrate at their own frequencies due to their inherent hardness. By detecting its amplitude, the ideal spin state representing the coupling can be detected.
The school's professor of physics, Gedo Bokad, explained that even near absolute zero (-273.15 degrees Celsius), temperature can have an impact on system behavior. In addition, system decoherence is also affected by phonon radiation (a kind of quantized acoustic emission), which relaxes the spin. In an atomic-optical quantum system, spin relaxation is like emitting a photon, but the spontaneous emission of atoms can be suppressed by an optical cavity. The optical cavity has a strong coupling mechanism that allows the photon to be in a sufficiently long cavity before disappearing. It is absorbed and emitted many times.
“This is the concept of nanomechanical resonance,†explains Bocard. “In our study, carbon nanotubes act as phonon cavities to produce effects similar to this. If the resonator model and spin reversal are needed Zeeman's energy phase resonance, quantum information will be transferred back and forth between spin and phonon; if not resonant, the lifetime of spin qubit will be extended, and the latter is the quantum information processor to be studied."
The important effect of this research is also that it can improve the performance of nanotubes in sensing applications. Bocard said that magnetic induction is based on the sensitivity of electron spins to external magnetic fields. When an electron spin couples with a mechanical resonator (such as a vibrating carbon nanotube that carries a charge by confining electrons), this signal can be read electronically. Conversely, when a small object is placed on a resonator, its resonant frequency will change, and the frequency change will affect the spin, which can be read by a spin-sensing telemetry detection device. Substance induction detection utilizes this frequency change.
The researchers stated that they are considering the next step in applying the research to the quantum information processing process and let the spin play a qubit role. “A fundamental problem in quantum mechanics is that it can be applied to large objects and keep them in a state of quantum superposition. We know that electrons and individual atoms have quantum properties, but macroscopic objects in our daily lives do not. The problem is that we The extent to which quantum laws can be applied.†Bocard said, “Our research is to generate quantum entanglement between a single electron spin and the mechanical motion of a larger object, and this result is expected to be studied in the spin. New quantum coherence, spin-spin coupling mechanisms, etc. will open new doors.†(Chang Lijun)
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