Approximating Many-Body Quantum States with Quantum Circuits and Measurements

Area of Science:

• Quantum Information Science
• Quantum Computing
• Many-Body Physics

Background:

• Preparing complex many-body quantum states is crucial for quantum information processing.
• Existing methods often require significant computational resources, scaling with system size.

Purpose of the Study:

• To develop resource-efficient protocols for preparing many-body quantum states using quantum circuits.
• To investigate methods for preparing specific states like W and Dicke states with reduced overhead.

Main Methods:

• Utilizing quantum circuits combined with local operations and classical communication (LOCC).
• Relaxing the constraint of exact state preparation to optimize resource usage.
• Implementing nonlocal, non-Clifford unitary operators efficiently.

Main Results:

• Developed protocols where W and Dicke state preparation requires circuit depth and ancilla count independent of system size.
• Introduced an efficient scheme for implementing specific nonlocal, non-Clifford unitary operators.
• Demonstrated potential for preparing eigenstates of spin models.

Conclusions:

• Resource-efficient preparation of many-body quantum states is achievable by relaxing exactness.
• The proposed methods offer significant advantages for preparing important quantum states and implementing complex quantum operations.
• These techniques have broad applicability in quantum simulation and computation.