You will be pleased to know that the majority of heat pumps are installed in homes whose exteriors stay above 0 kelvin year round. Also, in what I assume is an efficiency feature, most heat pumps do not allow operation in a zero Kelvin environment.
Also, to nit pick: Kelvins are not degrees and do not use a ° sign.
Are you trying to liquify vacuum? It's challenging. Try to use a heat pump based on the Casemir effect, fluctuating virtual particles violate the energy conservation of the system for short periods.
And, as a bonus efficiency feature, most heat pumps are installed with the condenser external to the home!
Yes, if you draw an imaginary box around the home and the outdoor/underground condenser, they're exactly 100% efficient, but if you only consider the inside of the home and ignore that the condenser is taking in heat energy from the outside, they're more than 100% efficient.
Just draw an imaginary line around my pocket book then. I pay for the energy I'm getting from the power station. Beyond capex, I don't pay for the energy I'm getting from the heat exchanger.
Also, to nit pick: Kelvins are not degrees and do not use a ° sign.