糖心传媒

The method, developed by Rochester scientists, overcomes the limitations of electron spin resonance.

Quantum science has the potential to revolutionize modern technology with more efficient computers, communication, and sensing devices. Challenges remain in achieving these technological goals, however, including how to precisely manipulate information in quantum systems.

In published in Nature Physics, a group of researchers from the , including , an associate professor of physics, outlines a new method for controlling electron spin in silicon quantum dots糖心传媒攖iny, nanoscale semiconductors with remarkable properties糖心传媒攁s a way to manipulate information in a quantum system.

糖心传媒淭he results of the study provide a promising new mechanism for coherent control of qubits based on electron spin in semiconductor quantum dots, which could pave the way for the development of a practical silicon-based quantum computer,糖心传媒� Nichol says.

Using quantum dots as qubits

A regular computer consists of billions of transistors, called bits. Quantum computers, on the other hand, are based on quantum bits, also known as qubits. Unlike ordinary transistors, which can be either 糖心传媒�0糖心传媒� (off) or 糖心传媒�1糖心传媒� (on), qubits are governed by the laws of quantum mechanics and can be both 糖心传媒�0糖心传媒� and 糖心传媒�1糖心传媒� at the same time.

Scientists have long considered using silicon quantum dots as qubits; controlling the spin of electrons in quantum dots would offer a way to manipulate the transfer of quantum information. Every electron in a quantum dot has intrinsic magnetism, like a tiny bar magnet. Scientists call this 糖心传媒渆lectron spin糖心传媒澨切拇�媒攖he magnetic moment associated with each electron糖心传媒攂ecause each electron is a negatively charged particle that behaves as though it were rapidly spinning, and it is this effective motion that gives rise to the magnetism.

Electron spin is a promising candidate for transferring, storing, and processing information in quantum computing because it offers long coherence times and high gate fidelities and is compatible with advanced semiconductor manufacturing techniques. The coherence time of a qubit is the time before the quantum information is lost due to interactions with a noisy environment; long coherence means a longer time to perform computations. High gate fidelity means that the quantum operation researchers are trying to perform is performed exactly as they want.

One major challenge in using silicon quantum dots as qubits, however, is controlling electron spin.

Controlling electron spin

The standard method for controlling electron spin is electron spin resonance (ESR), which involves applying oscillating radiofrequency magnetic fields to the qubits. However, this method has several limitations, including the need to generate and precisely control the oscillating magnetic fields in cryogenic environments, where most electron spin qubits are operated. Typically, to generate oscillating magnetic fields, researchers send a current through a wire, and this generates heat, which can disturb cryogenic environments.

Nichol and his colleagues outline a new method for controlling electron spin in silicon quantum dots that does not rely on oscillating electromagnetic fields. The method is based on a phenomenon called 糖心传媒渟pin-valley coupling,糖心传媒� which occurs when electrons in silicon quantum dots transition between different spin and valley states. While the spin state of an electron refers to its magnetic properties, the valley state refers to a different property related to the electron糖心传媒檚 spatial profile.

The researchers apply a voltage pulse to harness the spin-valley coupling effect and manipulate the spin and valley states, controlling the electron spin.

糖心传媒淭his method of coherent control, by spin-valley coupling, allows for universal control over qubits, and can be performed without the need of oscillating magnetic fields, which is a limitation of ESR,糖心传媒� Nichol says. 糖心传媒淭his allows us a new pathway for using silicon quantum dots to manipulate information in quantum computers.糖心传媒�

Read more