An optical trap for trapping and cooling atoms, the optical trap comprising: a vacuum chamber operable to provide a vacuum atmosphere in which atoms of an atomic species can be laser cooled via excitation of an electronic transition of the atomic species, referred to as the cooling transition; a laser source configured to generate laser light at a frequency detuned below the frequency of the cooling transition; an optical arrangement configured to manipulate the laser light to generate first, second and third beams with respective first, second and third beam widths, and to direct the first, second and third beams to propagate across the vacuum chamber along respective first, second and third incident beam paths that deviate from a mutually orthogonal arrangement in which they would each form an alignment angle of 45° to a reference axis, having instead respective first, second and third alignment angles of between 20° and 40° to the reference axis; and first, second and third reflectors arranged to reflect the first, second and third beams to propagate back across the vacuum chamber along their incident beam paths in respective first, second and third reflected beam paths that deviate from a retro-reflection, in which each reflected beam path would be coincident with its incident beam path, by respective first, second and third misalignment angles, the first, second and third misalignment angles (α, β, K) and beam widths having values that define a volume of intersection within the vacuum chamber traversed by the first, second and third beams both when propagating along their incident beam paths and their reflected beam paths. a vacuum chamber operable to provide a vacuum atmosphere in which atoms of an atomic species can be laser cooled via excitation of an electronic transition of the atomic species, referred to as the cooling transition; a laser source configured to generate laser light at a frequency detuned below the frequency of the cooling transition; an optical arrangement configured to manipulate the laser light to generate first, second and third beams with respective first, second and third beam widths, and to direct the first, second and third beams to propagate across the vacuum chamber along respective first, second and third incident beam paths that deviate from a mutually orthogonal arrangement in which they would each form an alignment angle of 45° to a reference axis, having instead respective first, second and third alignment angles of between 20° and 40° to the reference axis; and first, second and third reflectors arranged to reflect the first, second and third beams to propagate back across the vacuum chamber along their incident beam paths in respective first, second and third reflected beam paths that deviate from a retro-reflection, in which each reflected beam path would be coincident with its incident beam path, by respective first, second and third misalignment angles, the first, second and third misalignment angles (α, β, K) and beam widths having values that define a volume of intersection within the vacuum chamber traversed by the first, second and third beams both when propagating along their incident beam paths and their reflected beam paths.