  We report on a quantum thermodynamic method to purify a qubit on a quantum
processing unit (QPU) equipped with (nearly) identical qubits. Our starting
point is a three qubit design that emulates the well known two qubit swap
engine. Similar to standard fridges, the method would allow to cool down a
qubit at the expense of heating two other qubits. A minimal modification
thereof leads to a more practical three qubit design that allows for enhanced
refrigeration tasks, such as increasing the purity of one qubit at the expense
of decreasing the purity of the other two. The method is based on the
application of properly designed quantum circuits, and can therefore be run on
any gate model quantum computer. We implement it on a publicly available
superconducting qubit based QPU, and observe a purification capability down to
200 mK. We identify gate noise as the main obstacle towards practical
application for quantum computing.
