Non-adiabatic quantum control of quantum dot arrays with fixed exchange using Cartan decomposition

Area of Science:

• Quantum Information Science
• Condensed Matter Physics
• Quantum Computing

Background:

• Semiconductor spin qubits rely on short-range exchange coupling for operations.
• Existing spin shuttling protocols are limited by the significant minimal exchange coupling in many devices.
• Scalable quantum operations require efficient methods for transferring spin states between distant qubits.

Purpose of the Study:

• To develop a novel non-adiabatic spin shuttling method for long chains of quantum dots.
• To overcome the limitations imposed by significant minimal exchange coupling in semiconductor spin qubit systems.
• To enable efficient spin state transfer in scalable quantum computing architectures.

Main Methods:

• Extended previous work on double- and triple-dot systems to long chains of singly occupied quantum dots.
• Employed Cartan decomposition to simplify the interacting quantum system.
• Utilized dynamical invariants to design smooth, non-adiabatic control pulses.
• Considered implementation feasibility with modest control bandwidth.

Main Results:

• Successfully described a method for non-adiabatic spin state transfer in long quantum dot chains.
• Demonstrated a systematic approach to break down complex interacting problems.
• Designed control pulses suitable for experimental implementation in current devices.
• Discussed the extension of the method to two-dimensional lattices.

Conclusions:

• The proposed non-adiabatic shuttling method offers a practical solution for generating quantum operations between distant qubits in semiconductor systems.
• This approach addresses the limitations of existing protocols caused by significant minimal exchange coupling.
• The technique is extensible to more complex two-dimensional quantum dot arrays, paving the way for scalable quantum computing.