US 12,271,784 B2
Short-depth syndrome extraction circuits in 2D quantum architectures for hypergraph product codes
Nicolas Guillaume Delfosse, Bellevue, WA (US); Maxime Tremblay, Sherbrooke (CA); and Michael Edward Beverland, Seattle, WA (US)
Assigned to Microsoft Technology Licensing, LLC, Redmond, WA (US)
Filed by Microsoft Technology Licensing, LLC, Redmond, WA (US)
Filed on Mar. 31, 2021, as Appl. No. 17/219,331.
Claims priority of provisional application 63/130,115, filed on Dec. 23, 2020.
Prior Publication US 2022/0198311 A1, Jun. 23, 2022
Int. Cl. G06N 10/70 (2022.01); G06F 11/10 (2006.01); G06F 16/901 (2019.01)
CPC G06N 10/70 (2022.01) [G06F 11/1044 (2013.01); G06F 11/1048 (2013.01); G06F 16/9024 (2019.01)] 17 Claims
OG exemplary drawing
 
1. A method for extracting a syndrome from a quantum measurement circuit implementing a hypergraph product code (HPG), the method comprising:
preparing a readout qubit of the quantum measurement circuit in a known state, the readout qubit corresponding to a check qubit in the hypergraph product (HPG) code that is used in a stabilizer measurement to measure parity of an associated target set of data qubits;
prepare a row-based measurement gadget in the quantum measurement circuit by operations that include:
forming a cat state of a row of bridge ancilla qubits, the row of bridge ancilla qubits including a least one ancilla qubit that is a nearest-neighbor qubit to the readout qubit and at least one ancilla qubit that is a nearest-neighbor to each of the data qubits in a first subset of the target set of data qubits; and
entangling the cat state with the first subset of the target set of data qubits in a same row of the quantum measurement circuit as the readout qubit;
prepare a column-based measurement gadget in the quantum measurement circuit, the column-based measurement gadget entangling the readout qubit with a second subset of the target set of data qubits in a same column of the quantum measurement circuit as the readout qubit; and
measuring the readout qubit to extract the parity of the target set of data qubits.