Phase Locking between Different Partial Waves in Atom-Ion Spin-Exchange Collisions

• Published in: Physical review letters Vol. 121; no. 17; p. 173402
• Main Authors: Sikorsky, Tomas, Morita, Masato, Meir, Ziv, Buchachenko, Alexei A, Ben-Shlomi, Ruti, Akerman, Nitzan, Narevicius, Edvardas, Tscherbul, Timur V, Ozeri, Roee
• Format: Journal Article
• Language: English
• Published: United States American Physical Society 26-10-2018
• Subjects: Collisions; Quantum interference effects; Qubits (quantum computing); Spin dynamics; Spin exchange; Spin-orbit interactions
• ISSN: 0031-9007; 1079-7114
• DOI: 10.1103/PhysRevLett.121.173402

We present a joint experimental and theoretical study of spin dynamics of a single ^{88}Sr^{+} ion colliding with an ultracold cloud of Rb atoms in various hyperfine states. While spin exchange between the two species occurs after 9.1(6) Langevin collisions on average, spin relaxation of the Sr^{+} ion Zeeman qubit occurs after 48(7) Langevin collisions, which is significantly slower than in previously studied systems due to a small second-order spin-orbit coupling. Furthermore, a reduction of the endothermic spin-exchange rate is observed as the magnetic field is increased. Interestingly, we find that while the phases acquired when colliding on the spin singlet and triplet potentials vary largely between different partial waves, the singlet-triplet phase difference, which determines the spin-exchange cross section, remains locked to a single value over a wide range of partial waves, which leads to quantum interference effects.