Observing complementary Lucas sequences using non-Hermitian zero modes

The Lucas sequences are integers defined by a homogeneous recurrence relation.

They include the well-known Fibonacci numbers, which appear abundantly in nature.

The complementary Lucas numbers, defined by the same recurrence relation, are less well-known.

In this work, we show that such complementary Lucas sequences can be observed simultaneously on the same physical platform, using zero modes in one-dimensional system(s) coupled to a non-Hermitian reservoir.

When the latter consists solely of gain and loss modulated non-Hermiticity, the two Lucas sequences can manifest as a linearly localized edge state and a constant-intensity mode, respectively.

When the reservoir features asymmetric couplings as well, more general Lucas sequences can be realized either directly on one sublattice in the reservoir or by reconstructing the wave function on both sublattices.

Finally, if we allow, in addition, an alternate frequency detuning in the reservoir, all Lucas sequences can be observed in principle, including the Fibonacci and Lucas numbers.