Figure 2. Magnetic field dependence.

(a) Shift of polariton energies with applied voltage for polaritons excited with (yellow) and (blue) at B_z=5 T; solid lines are fits to second-order polynomials (−d_VV_G−α_V, blue: d_V=3.0 × 10⁻⁶ eV V⁻¹, α_V=1.8 × 10⁻⁶ eV V⁻², yellow: d_V=−5.2 × 10⁻⁶ eV V⁻¹, α_V=1.9 × 10⁻⁶ eV V⁻²). Error bars represent 1 s.d. of the polariton resonance energy extracted from a fit of the data to a reflection lineshape (see Supplementary Note 3). Grey dashed lines indicate the voltage at which maximum energy occurs for the two parabolas, the grey arrow indicates the difference between them (ΔV). (b) Using data such as a at different B_z, difference between the extracted voltage (ΔV) at which maximum energy occurs for and excitations. (c) Change in α_V (polarizability) with B_z (filled squares, left axis, and grey curve). Change of lower polariton resonant energy with B_z at V_G=0 V (filled circles, right axis, and red curve) from the value at B_z=0 T. Yellow and blue data points are data for and , respectively. (d) Difference between extracted d_V values (electric dipole moment) for polaritons propagating with and . For b–d, error bars are the estimated standard deviations of the mean for three repetitions of the experiment (some error bars are smaller than the markers), and the solid lines are results of a numerical calculation (see Supplementary Note 4).