Abstract: Scalable, parallelizable quantum error correction on surface codes can be performed using a decoder graph. Overlapping decoder graph windows can be generated using the decoder graph. First corrections can be independently determined for each of the overlapping decoder graph windows. First core corrections can be retained for core regions of each of the overlapping decoder graph windows. Non-overlapping decoder graph windows can be generated using the decoder graph. The temporal boundaries of the non-overlapping decoder graph windows can be the temporal boundaries of the corrected core regions of the overlapping decoder graph windows. Second corrections can be independently determined for each of the non-overlapping decoder graph windows based on the temporal boundaries of the corrected core regions. The first core corrections and the second corrections can be combined to form a complete set of corrections for the decoder graph.

Abstract: Methods and techniques are provided for simulating a quantum circuit. A system can perform operations including generating a transformed Hamiltonian corresponding to a quantum circuit. The transformed Hamiltonian can include transformed local and coupling Hamiltonians. Generation of the transformed Hamiltonian can include obtaining a charge coupling matrix and a flux coupling matrix of an original Hamiltonian corresponding to the quantum circuit and at least partially diagonalizing the charge coupling matrix and the flux coupling matrix. The operations can further include determining a limited eigenbasis including a number of eigenvectors of the transformed local Hamiltonian, projecting the transformed coupling Hamiltonian and the transformed local Hamiltonian onto the limited eigenbasis, and generating an at least partially decoupled Hamiltonian by combining the projection of the transformed coupling and local Hamiltonians.

Abstract: Systems and methods are provided for coordinating decisions between noncommunicating parties using quantum physics. The procedure includes recognizing and identifying features of a coordinating decisions between non-communicating parties (CDNP) problem, expressing these features in a precise and mathematical manner, finding a solution using quantum states and measurements, and physically implementing the solution. Since quantum mechanics can violate Bell inequalities, quantum solutions to a CDNP problem have advantages over non-quantum solutions.

Abstract: One embodiment described herein provides a system and method for simulating behavior of a quantum circuit that includes a plurality of quantum gates. During operation, the system receives information that represents the quantum circuit and constructs an undirected graph corresponding to the quantum circuit. A respective vertex within the undirected graph corresponds to a distinct variable in a Feynman path integral used for computing amplitude of the quantum circuit, and a respective edge corresponds to one or more quantum gates. The system identifies a vertex within the undirected graph that is coupled to at least two two-qubit quantum gates; simplifies the undirected graph by removing the identified vertex, thereby effectively removing the two-qubit quantum gates coupled to the identified vertex; and evaluates the simplified undirected graph, thereby facilitating simulation of the behavior of the quantum circuit.

Abstract: Systems and methods are provided for coordinating decisions between noncommunicating parties using quantum physics. The procedure includes recognizing and identifying features of a coordinating decisions between non-communicating parties (CDNP) problem, expressing these features in a precise and mathematical manner, finding a solution using quantum states and measurements, and physically implementing the solution. Since quantum mechanics can violate Bell inequalities, quantum solutions to a CDNP problem have advantages over non-quantum solutions.

Abstract: One embodiment described herein provides a system and method for simulating behavior of a quantum circuit that includes a plurality of quantum gates. During operation, the system receives information that represents the quantum circuit and constructs an undirected graph corresponding to the quantum circuit. A respective vertex within the undirected graph corresponds to a distinct variable in a Feynman path integral used for computing amplitude of the quantum circuit, and a respective edge corresponds to one or more quantum gates. The system identifies a vertex within the undirected graph that is coupled to at least two two-qubit quantum gates; simplifies the undirected graph by removing the identified vertex, thereby effectively removing the two-qubit quantum gates coupled to the identified vertex; and evaluates the simplified undirected graph, thereby facilitating simulation of the behavior of the quantum circuit.

Abstract: One embodiment described herein provides a system and method for simulating behavior of a quantum circuit that includes a plurality of quantum gates. During operation, the system receives information that represents the quantum circuit and constructs an undirected graph corresponding to the quantum circuit. A respective vertex within the undirected graph corresponds to a distinct variable in a Feynman path integral used for computing amplitude of the quantum circuit, and a respective edge corresponds to one or more quantum gates. The system identifies a vertex within the undirected graph that is coupled to at least two two-qubit quantum gates; simplifies the undirected graph by removing the identified vertex, thereby effectively removing the two-qubit quantum gates coupled to the identified vertex; and evaluates the simplified undirected graph, thereby facilitating simulation of the behavior of the quantum circuit.

Abstract: Systems and methods are provided for coordinating decisions between noncommunicating parties using quantum physics. The procedure includes recognizing and identifying features of a coordinating decisions between non-communicating parties (CDNP) problem, expressing these features in a precise and mathematical manner, finding a solution using quantum states and measurements, and physically implementing the solution. Since quantum mechanics can violate Bell inequalities, quantum solutions to a CDNP problem have advantages over non-quantum solutions.

Abstract: One embodiment described herein provides a system and method for simulating behavior of a quantum circuit that includes a plurality of quantum gates. During operation, the system receives information that represents the quantum circuit and constructs an undirected graph corresponding to the quantum circuit. A respective vertex within the undirected graph corresponds to a distinct variable in a Feynman path integral used for computing amplitude of the quantum circuit, and a respective edge corresponds to one or more quantum gates. The system identifies a vertex within the undirected graph that is coupled to at least two two-qubit quantum gates; simplifies the undirected graph by removing the identified vertex, thereby effectively removing the two-qubit quantum gates coupled to the identified vertex; and evaluates the simplified undirected graph, thereby facilitating simulation of the behavior of the quantum circuit.

Abstract: A method of generating a random bit string includes receiving a binary input string, creating copies of the binary input string received from the min-entropy source, and providing each of the copies of the binary input string to one of a plurality of randomness extractors. The method further includes, for each randomness extractor, providing the respective extracted output binary string to one of a plurality of quantum devices, where each of the plurality of quantum devices is configured to (i) receive the extracted output binary string as a locally random input signal string, random only to that respective quantum device, and (ii) transform the received locally random input string into a globally random output signal string. Still further, the method includes combining the plurality of globally random output signal strings from the plurality of quantum devices to generate the random bit string.

Abstract: A method of generating a sequence of random bits includes receiving a binary input signal from an input signal source and coupling the binary input signal into a plurality of components of the quantum device to initiate a random bit generation cycle. Each of the plurality of components of the quantum device produces a binary output during the random bit generation cycle, and the quantum device is configured to operate according to a non-local game during the random bit generation cycle. The method further includes maintaining isolation of the plurality of components of the quantum device during the random bit generation cycle, obtaining a plurality of binary outputs from the plurality of components of the quantum device, and producing a random bit based on the plurality of binary outputs and the binary input signal. After the random bit generation cycle, communication among the plurality of components of the quantum device is allowed.

Abstract: A method of generating a random bit string includes receiving a binary input string, creating copies of the binary input string received from the min-entropy source, and providing each of the copies of the binary input string to one of a plurality of randomness extractors. The method further includes, for each randomness extractor, providing the respective extracted output binary string to one of a plurality of quantum devices, where each of the plurality of quantum devices is configured to (i) receive the extracted output binary string as a locally random input signal string, random only to that respective quantum device, and (ii) transform the received locally random input string into a globally random output signal string. Still further, the method includes combining the plurality of globally random output signal strings from the plurality of quantum devices to generate the random bit string.

Abstract: A method of generating a sequence of random bits includes receiving a binary input signal from an input signal source and coupling the binary input signal into a plurality of components of the quantum device to initiate a random bit generation cycle. Each of the plurality of components of the quantum device produces a binary output during the random bit generation cycle, and the quantum device is configured to operate according to a non-local game during the random bit generation cycle. The method further includes maintaining isolation of the plurality of components of the quantum device during the random bit generation cycle, obtaining a plurality of binary outputs from the plurality of components of the quantum device, and producing a random bit based on the plurality of binary outputs and the binary input signal. After the random bit generation cycle, communication among the plurality of components of the quantum device is allowed.