Repeated quantum error correction on a continuously encoded qubit by real-time feedback

Kavli Affiliate: Tim H. Taminiau

| First 5 Authors: Julia Cramer, Norbert Kalb, M. Adriaan Rol, Bas Hensen, Machiel S. Blok

| Summary:

Reliable quantum information processing in the face of errors is a major
fundamental and technological challenge. Quantum error correction protects
quantum states by encoding a logical quantum bit (qubit) in multiple physical
qubits. To be compatible with universal fault-tolerant computations, it is
essential that the states remain encoded at all times and that errors are
actively corrected. Here we demonstrate such active error correction on a
continuously protected qubit using a diamond quantum processor. We encode a
logical qubit in three long-lived nuclear spins, repeatedly detect phase errors
by non-destructive measurements using an ancilla electron spin, and apply
corrections on the encoded state by real-time feedback. The actively
error-corrected qubit is robust against errors and multiple rounds of error
correction prevent errors from accumulating. Moreover, by correcting correlated
phase errors naturally induced by the environment, we demonstrate that encoded
quantum superposition states are preserved beyond the dephasing time of the
best physical qubit used in the encoding. These results establish a powerful
platform for the fundamental investigation of error correction under different
types of noise and mark an important step towards fault-tolerant quantum
information processing.

| Search Query: ArXiv Query: search_query=au:”Tim H. Taminiau”&id_list=&start=0&max_results=10

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