  Recent development of mixed-state encoding (MSE) allows pure-state logical
information to be encoded by a bosonic (continuous-variable) system in mixed
physical state. Despite interest due to its counter-intuitiveness, the utility
of the current MSE scheme is limited due to several operational drawbacks,
namely redundant information carrier, probabilistic initialisation, and
requirement of discrete-variable measurement. In this work, we present a
simplified MSE that does not suffer from any of these drawbacks. Specifically,
our protocol encodes each qubit by only one mixed-state bosonic mode, and the
logical basis can be deterministically initialised from thermal equilibrium.
All logical operations of this encoding can be performed with
continuous-variable interaction and measurement only. Without the necessity of
ground state cooling, our proposal could broaden the set of candidate systems
for implementing quantum computers, and reduce the reliance on demanding
refrigerating facility for current quantum computing architectures.
Additionally, our protocol can enhance the noise tolerance of logical qubit
even if the system can be efficiently cooled.
