QECC takes &quot;logical qubits on a larger space&quot; to &quot;corrected qubits on a smaller space&quot;. So while there is entropy production on the entire space (2nd law thermo), it is still possible to have entropy reduction locally.<p>Eg: 
0) &quot;1 important qubit in some specific pure state&quot; (entropy=0) + &quot;4 ancillary qubits in some known but unimportant state&quot;(entropy=0) are made using a 1to5 QECC into:<p>1) 1 logical qubit(made of 5-qubits) in a pure state (entropy=0)<p>2) Presence of noise: 5-qubits now in mixed-state (entropy=a&gt;0)<p>3) Error correction on 5-qubits turning them into:<p>4) &quot;1 important qubit in some specific pure state&quot;(entropy=0) + &quot;4 ancillary qubits in some now-random states&quot; (entropy&gt;=a&gt;0)