In the case of a particle in a potential of the form \( V(x) = \frac{1}{2} m \omega^2 x^2 \), the energy levels for the quantum harmonic oscillator are given by:
\[
E_n = \left(n + \frac{1}{2}\right) \hbar \omega \quad \text{where} \quad n = 0, 1, 2, \dots
\]
For the potential well defined on \( x > 0 \) (i.e., a half-harmonic oscillator), the energy levels are slightly altered due to the boundary condition at \( x = 0 \) (the infinite potential barrier). In this case, only the odd wavefunctions of the full harmonic oscillator are allowed, so the energy levels become:
\[
E_n = \left(n + \frac{1}{2}\right) \hbar \omega \quad \text{for odd } n
\]
The lowest energy level corresponds to \( n = 1 \):
\[
E_1 = \frac{3}{2} \hbar \omega
\]
The next higher level is at \( n = 3 \):
\[
E_3 = \frac{7}{2} \hbar \omega
\]
The ratio of the energies is:
\[
\frac{E_1}{E_3} = \frac{\frac{3}{2} \hbar \omega}{\frac{7}{2} \hbar \omega} = \frac{3}{7}
\]