Methods and apparatus for automatic qubit calibration. In one aspect, a method includes obtaining a plurality of qubit parameters and data describing dependencies of the plurality of qubit parameters on one or more other qubit parameters; identifying a qubit parameter; selecting a set of qubit parameters that includes the identified qubit parameter and one or more dependent qubit parameters; processing one or more parameters in the set of qubit parameters in sequence according to the data describing dependencies, comprising, for a parameter in the set of qubit parameters: performing a calibration test on the parameter; and performing a first calibration experiment or a diagnostic calibration algorithm on the parameter when the calibration test fails.

One superconducting qubit device package disclosed herein includes a die having a first face and an opposing second face, and a package substrate having a first face and an opposing second face. The die includes a quantum device including a plurality of superconducting qubits and a plurality of resonators on the first face of the die, and a plurality of conductive pathways coupled between conductive contacts at the first face of the die and associated ones of the plurality of superconducting qubits or of the plurality of resonators. The second face of the package substrate also includes conductive contacts. The device package further includes first level interconnects disposed between the first face of the die and the second face of the package substrate, coupling the conductive contacts at the first face of the die with associated conductive contacts at the second face of the package substrate.

One superconducting qubit device package disclosed herein includes a die having a first face and an opposing second face, and a package substrate having a first face and an opposing second face. The die includes a quantum device including a plurality of superconducting qubits and a plurality of resonators on the first face of the die, and a plurality of conductive pathways coupled between conductive contacts at the first face of the die and associated ones of the plurality of superconducting qubits or of the plurality of resonators. The second face of the package substrate also includes conductive contacts. The device package further includes first level interconnects disposed between the first face of the die and the second face of the package substrate, coupling the conductive contacts at the first face of the die with associated conductive contacts at the second face of the package substrate.

Bitcoins and the underlying blockchain technology are one of the main innovations in building decentralized applications. The effects of quantum computing on this technology are analyzed in general. Provided herein are effective solutions to address security vulnerabilities in a blockchain-based system that can be exploited by a quantum attacker.

Bitcoins and the underlying blockchain technology are one of the main innovations in building decentralized applications. The effects of quantum computing on this technology are analyzed in general. Provided herein are effective solutions to address security vulnerabilities in a blockchain-based system that can be exploited by a quantum attacker.

Methods, systems, and apparatus for solving computational tasks using quantum computing resources. In one aspect a method includes receiving, at a quantum formulation solver, data representing a computational task to be performed; deriving, by the quantum formulation solver, a formulation of the data representing the computational task that is formulated for a selected type of quantum computing resource; routing, by the quantum formulation solver, the formulation of the data representing the computational task to a quantum computing resource of the selected type to obtain data representing a solution to the computational task; generating, at the quantum formulation solver, output data including data representing a solution to the computational task; and receiving, at a broker, the output data and generating one or more actions to be taken based on the output data.

Methods, systems, and apparatus for solving computational tasks using quantum computing resources. In one aspect a method includes receiving, at a quantum formulation solver, data representing a computational task to be performed; deriving, by the quantum formulation solver, a formulation of the data representing the computational task that is formulated for a selected type of quantum computing resource; routing, by the quantum formulation solver, the formulation of the data representing the computational task to a quantum computing resource of the selected type to obtain data representing a solution to the computational task; generating, at the quantum formulation solver, output data including data representing a solution to the computational task; and receiving, at a broker, the output data and generating one or more actions to be taken based on the output data.

In some embodiments, one or more unitary-valued functions are generated by a classical computer generating using projectors with a predetermined number of significant bits. A quantum computing device is then configured to implement the one or more unitary-valued functions. In further embodiments, a quantum circuit description for implementing quantum signal processing that decomposes complex-valued periodic functions is generated by a classical computer, wherein the generating further includes representing approximate polynomials in a Fourier series with rational coefficients. A quantum computing device is then configured to implement a quantum circuit defined by the quantum circuit description.

In some embodiments, one or more unitary-valued functions are generated by a classical computer generating using projectors with a predetermined number of significant bits. A quantum computing device is then configured to implement the one or more unitary-valued functions. In further embodiments, a quantum circuit description for implementing quantum signal processing that decomposes complex-valued periodic functions is generated by a classical computer, wherein the generating further includes representing approximate polynomials in a Fourier series with rational coefficients. A quantum computing device is then configured to implement a quantum circuit defined by the quantum circuit description.

A highly parallelized parallel tempering technique for simulating dynamic systems, such as quantum processors, is provided. Replica exchange is facilitated by synchronizing grid-level memory. Particular implementations for simulating quantum processors by representing cells of qubits and couplers in grid-, block-, and thread-level memory are discussed. Parallel tempering of such dynamic systems can be assisted by modifying replicas based on isoenergetic cluster moves (ICMs). ICMs are generated via secondary replicas which are maintained alongside primary replicas and exchanged between blocks and/or generated dynamically by blocks without necessarily being exchanged. Certain refinements, such as exchanging energies and temperatures through grid-level memory, are also discussed.