SQUIDs are used extensively across the world of precision measurement in physics and many other sciences, including earth science studies and medicine, providing some of the most precise measurements possible. The paper will discuss some of the limits to SQUID measurements which emerge in these various fields. One of the newer areas of interest is the use of SQUIDs to measure the properties of nanomagnetic particles or even single spins. This is driven by the needs of future ultra high density magnetic storage and quantum information processing. The paper will focus on this issue and will propose some hard limits as well as some means by which the present state-of-the-art may be extended towards those limits.
Spin state detection is a key but very challenging step for any spin-based solid-state quantum computing technology. In fullerene based quantum computer technologies, we here propose to detect the single spin inside a fullerene by transferring the quantum information from the endohedral spin to the ground states of a molecular nanomagnet Fe
8, with large spin S=10. We show how to perform the required SWAP operation and how to read out the information through state-of-the-art techniques such as micro-SQUID.
Spin state detection is a key but very challenging step for any spin-based solid-state quantum computing technology. In fullerene-based quantum computer technologies, we here propose to detect the single spin inside a fullerene by transferring the quantum information from the endohedral spin to the ground states of a molecular nanomagnet Fe 8 , with large spin S = 10. We show how to perform the required SWAP operation and how to read out the information through state-of-the-art techniques such as micro-SQUID.