Magnetically-induced magic polarization in the ground state of ¹⁷¹Yb⁺

In trapped ion quantum computers, light shifts induced by the lasers used to effect quantum gates can lead to dephasing of the quantum information stored in spectator ions, which can lead to errors. However, with correct magnetic field geometry and polarization of the gate laser, Zeeman-induced state mixing creates a "magic" polarization, in which the qubit becomes insensitive to the AC Stark effect caused by the gate laser. While this effect is well-known for preserving coherence in optical dipole traps [1], it has not been broadly applied in trapped ion systems. We present an observation of this magic polarization effect in the ground state clock qubit of a trapped ¹⁷¹Yb ion, demonstrate a marked increase in coherence time, and discuss its application to other trapped ion species.

[1] N. Lundblad, M. Schlosser, Porto J. V. Experimental observation of magic-wavelength behavior of ⁸⁷Rb atoms in an optical lattice. Phys. Rev. A 81, 031611 (2010)