Although intrinsic topological superconductivity appears probable in UTe2, its superconductive order parameter Δk has been difficult to establish. If spin-triplet, it should have odd parity so that Δ(-k)=-Δ(k) . A distinctive identifier of such nodal spin-triplet superconductors is the appearance of an Andreev bound state on surfaces parallel to a nodal axis, in the form of a topological quasiparticle surface band (QSB). Moreover, theory shows that specific QSB characteristics observable in tunneling to an s-wave superconductor distinguish between chiral and non-chiral Δ(k) . To explore such phenomena in UTe2, we employ s-wave superconductive STM scan-tip imaging and discover a distinct TSB signature, an intense zero-energy Andreev conductance maximum at the (0-11) crystal termination (Nature 628, 921 (2023)). Development of the zero-energy Andreev conductance peak into two finite-energy particle-hole symmetric conductance maxima as the tunnel barrier is reduced, then signifies that UTe2 superconductivity is non-chiral. These data imply that the superconductive Δ(k) is the odd-parity non-chiral B3u state (Science 388, 938 (2025)).

The parity of Δ(k) might also be established by using Bogoliubov quasiparticle interference imaging (QPI). However, in an intrinsic topological superconductor QPI should be dominated by topological QSB for energies within the superconductive energy gap |E| ≤ Δ . By using a superconducting scan-tip to achieve ~10 μeV energy resolution QPI for UTe2 studies, we discover and visualize the in-gap quasiparticle interference patterns of its QSB. Specifically, a band of Bogoliubov quasiparticles appears below Tc at a characteristic sextet qi:i=1-6 of interference wavevectors. From these we establish that QSB dispersions occur only for energies |E|≤Δmax and within the range of Fermi momenta projected onto the (0-11) crystal surface. A theoretical framework developed to understand the QPI signatures of a QSB at this (0-11) UTe2 surface yields predictions consistent with the experimental results – again, if the bulk Δ(k) exhibits time-reversal conserving, odd-parity, a-axis nodal, B3u symmetry (Nature Physics 21, 1555 (2025)).