Energy as a function of the dimensionless spin–orbit coupling parameter β for the case of equal frequencies ω = ω<sub><em>x</em></sub> = ω<sub><em>y</em></sub> with no Zeeman shift (left panel) and including a Zeeman shift of magnitude μ<em>B</em> = ω

<p><strong>Figure 1.</strong> Energy as a function of the dimensionless spin–orbit coupling parameter β for the case of equal frequencies ω = ω<sub><em>x</em></sub> = ω<sub><em>y</em></sub> with no Zeeman shift (left panel) and including a Zeeman shift of magnitude μ<em>B</em> = ω.</p> <p><strong>Abstract</strong></p> <p>We consider a spin–orbit coupled system of particles in an external trap that is represented by a deformed harmonic oscillator potential. The spin–orbit interaction is a Rashba interaction that does not commute with the trapping potential and requires a full numerical treatment in order to obtain the spectrum. The effect of a Zeeman term is also considered. Our results demonstrate that variable spectral gaps occur as a function of strength of the Rashba interaction and deformation of the harmonic trapping potential. The single-particle density of states and the critical strength for superfluidity vary tremendously with the interaction parameter. The strong variations with Rashba coupling and deformation imply that the few- and many-body physics of spin–orbit coupled systems can be manipulated by variation of these parameters.</p>