Progress Towards Using Optical Forces to Manipulate Phonon Modes of an Ion Chain

Ion traps are a leading platform for quantum computing due to their long coherence times and high fidelity control. A chain of ions provides any-to-any connectivity through its motional mode structure; as the number of ions in a chain increases, the number of motional modes of the ion chain increases. These shared motional modes mediate entangling gates. The ability to break and reconfigure the motional modes of ion chains would be extremely useful to parallelize operations and to scale up ion traps. Current state of the art QCCD architectures physically move ions via shuttling to break up the long ion chains. However, shuttling is a slow process that heats up the ions’ motion, leading to gate errors. We propose the use of optical forces to manipulate and control the motional mode structure of a chain of ions. We explore in simulation the use of a 532 nm laser to optically trap 40 Ca⁺ ions in a linear paul trap. Assuming 1.5 mW of optical power, we can achieve optical trapping frequencies along the transverse and laser axis of 𝛚_t ~ 2𝜋 x 400 kHz and 𝛚_z ~ 2𝜋 x 100 kHz with a low scattering rate of ~ 18 s^-1. This optical trap will change the motional mode structure of the chain of ions. Our simulation will help us explore virtually segmenting an ion chain and the expected heating rates from doing so. We will present simulation results showing a section of the chain whose motion is decoupled from the rest of the ion chain.