Rigetti & Co, LLC

Eyob Alebachew Sete

Chad Tyler Rigetti

Matthew J Reagor

William J Zeng

Shane Arthur Caldwell

Nikolas Anton Tezak

Michael James Curtis

Benjamin Jacob Bloom

Nasser Alidoust

Peter Jonathan Karalekas

Dane Christoffer Thompson

Marcus Palmer Da Silva

Colm Andrew Ryan

Alexander Papageorge

Deanna Margo Abrams

Nicolas Didier

Sabrina Sae Byul Hong

Prasahnt Sivarajah

Mehrnoosh Vahidpour

Jean-Luc François-Xavier Orgiazzi

Alexei N Marchenkov

Alexei N Marchenokov

Michael Karunendra Selvanayagam

Stefano Poletto

Mark Field

Mehmoosh Vahidpour

Riccardo Manenti

Angela Q Chen

Shobhan Kulshreshtha

Xiqiao Wang

David Pappas

Joshua Yousouf Mutus

In a general aspect, a superconducting quantum processing unit includes a first qubit device, a second qubit device, and a tunable floating coupler device coupled between the first and second qubit devices. Values of a coupling strength of the first and second qubit devices at a plurality of operating points of the tunable floating coupler device are measured. The operating points correspond to respective values of a magnetic flux applied to the tunable floating coupler device. Based on the measured values of the coupling strength, a parking value of the magnetic flux is identified. The parking value of the magnetic flux corresponds to a magnitude of the coupling strength being less than or equal to a threshold value; the threshold value is associated with a target gate fidelity for the superconducting quantum processing unit.

Controlling a tunable floating coupler device in a superconducting quantum processing unit

In some implementations, a quantum error-correction technique includes applying a first set of two-qubit gates to qubits in a lattice cell, and applying a second, different set of two-qubit gates to the qubits in the lattice cell. The qubits in the lattice cell include data qubits and ancilla qubits, and the ancilla qubits reside between respective nearest-neighbor pairs of the data qubits. After the first and second sets of two-qubit gates have been applied, measurement outcomes of the ancilla qubits are obtained, and the parity of the measurement outcomes is determined.

Quantum error-correction in microwave integrated quantum circuits

In a general aspect, junction properties of tunnel junctions are altered by voltage-assisted annealing processes. In some cases, a method includes obtaining a circuit comprising a tunnel junction, modifying a junction resistance of the tunnel junction by applying a voltage across the tunnel junction, and obtaining a measured value of the junction resistance. The tunnel junction may include a metal and a metal oxide.

Voltage-assisted annealing to alter tunnel junction properties

In a general aspect, a quantum logic gate is performed in a quantum computing system. In some cases, a pair of qubits are defined in a quantum processor; the pair of qubits can include a first qubit defined by a first qubit device in the quantum processor and a second qubit defined by a tunable qubit device in the quantum processor. A quantum logic gate can be applied to the pair of qubits by communicating a control signal to a control line coupled to the tunable qubit device. The control signal can be configured to modulate a transition frequency of the tunable qubit device at a modulation frequency, and the modulation frequency can be determined based on a transition frequency of the first qubit device.

Parametrically activated quantum logic gates

In a general aspect, calibration is performed in a quantum computing system. In some cases, domains of a quantum computing system are identified, where the domains include respective domain control subsystems and respective subsets of quantum circuit devices in a quantum processor of the quantum computing system. Sets of measurements are obtained from one of the domains and stored in memory. Device characteristics of the quantum circuit devices of the domain are obtained based on the set of measurements, and the device characteristics are stored in a memory of the control system. Quantum logic control parameters for the subset of quantum circuit devices of the domain are obtained based on the set of measurements and stored in memory.

Performing a calibration process in a quantum computing system

In a general aspect, a quantum error-correction technique includes applying a first set of two-qubit gates to qubits in a lattice cell, and applying a second, different set of two-qubit gates to the qubits in the lattice cell. The qubits in the lattice cell include data qubits and ancilla qubits, and the ancilla qubits reside between respective nearest-neighbor pairs of the data qubits. After the first and second sets of two-qubit gates have been applied, measurement outcomes of the ancilla qubits are obtained, and the parity of the measurement outcomes is determined.

A quantum computing system that includes a quantum circuit device having at least one operating frequency; a first substrate having a first surface on which the quantum circuit device is disposed; a second substrate having a first surface that defines a recess of the second substrate, the first and second substrates being arranged such that the recess of the second substrate forms an enclosure that houses the quantum circuit device; and an electrically conducting layer that covers at least a portion of the recess of the second substrate.

Microwave integrated quantum circuits with vias and methods for making the same

Quantum logic control pulse determination

In a general aspect, a qubit device includes two circuit loops. In some aspects, a first circuit loop includes a first Josephson junction, a second circuit loop includes a second Josephson junction, and the first and second loops are configured to receive a magnetic flux that defines a transition frequency of a qubit device. In some aspects, a quantum integrated circuit includes an inductor connected between a first circuit node and a second circuit node; the first Josephson junction connected in parallel with the inductor between the first circuit node and the second circuit node; and the second Josephson junction connected in parallel with the inductor between the first circuit node and the second circuit node.

Flux-tunable qubit device with multiple Josephson junctions

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Walnut Creek, CA, United States of America

Eyob Alebachew Sete