Stark quenching of rovibrational states of ${\mathrm{H}}_2^{+}$ due to motion in a magnetic field

The motional electric field experienced by an ${\mathrm{H}}_2^{+}$ ion moving in a magnetic field induces an electric dipole, so that one-photon dipole transitions between rovibrational states become allowed. Field-induced spontaneous decay rates are calculated for a wide range of states. For an ion stored in a high-field ($B\sim 10$ T) Penning trap, it is shown that the lifetimes of excited rovibrational states can be shortened by typically 1–3 orders of magnitude by placing the ion in a large cyclotron orbit. This can greatly facilitate recently proposed [E. G. Myers, Phys. Rev. A 98, 010101 (2018).] high-precision spectroscopic measurements on ${\mathrm{H}}_2^{+}$ and its antimatter counterpart for tests of $CPT$ symmetry.

Figure 1

Normalized decay rate $A_{v,L,M,v^{\prime },L^{\prime }}/{\overline{A}}_{v,L,v^{\prime },L^{\prime }}$ for $L=27,L^{\prime }=25$ (blue circles), $L=25,L^{\prime }=27$ (red triangles), and $v=1,L=25,v^{\prime }=0,L^{\prime }=25$ (green squares). Note that the $M$ dependence is independent of $v$ and $v^{\prime }$ for $\mathrm{\Delta }L=\pm 2$ [see Eq. (26)], but not for $\mathrm{\Delta }L=0$ [Eq. (28)].

Figure 2

Stark lifetimes of ${\mathrm{H}}_2^{+}$ rovibrational states for an ion in a cyclotron orbit of radius $r_c=2$ mm in a magnetic field $B_0=8.5$ T are shown by thick red lines. For comparison, the zero-field lifetimes (taken from [24]) are shown by thin black lines. Circles, squares, diamonds, and triangles, respectively, stand for $v=0$, 1, 4, and 8.