Central controller for a quantum system
A quantum computing system having a central controller with improved latency executes a first instruction at a processing unit of the central controller. The central controller interconnects a plurality of control entities for configuring and measuring a plurality of qubits. A set of selected channels carry measurement results for a first quantum computation by the plurality of qubits. When the first instruction is a multi-channel-receive instruction, the system stalls the processing unit from executing any further instructions until each channel of the set of two or more selected channels has provided an input from a remote peer. Different channels in the set of selected channels are examined simultaneously. The system resumes execution at the processing unit of a second instruction after the stalling.
1 . A computer-implemented method comprising:
executing a first instruction at a processing unit of a first computing device, wherein the processing unit implements a central controller that interconnects a plurality of drive nodes and measuring entities for respectively configuring and measuring a plurality of transmon qubits in a superconducting quantum computing system, wherein respective drive nodes are separate computing devices, and a measuring entity is a separate device to measure and readout multiple transmon qubits; and
upon determining that the first instruction is a multi-channel-receive instruction:
stalling the processing unit from executing any further instructions until each channel of a set of selected channels has provided an input from a remote peer measuring entity, wherein different channels in the set of selected channels are examined simultaneously; and
resuming execution at the processing unit of a second instruction after the stalling;
wherein each channel of the set of selected channels carries a measurement result for a first quantum computation by the plurality of transmon qubits from the measuring entity;
wherein executing the second instruction causes the central controller to send a message, via the respective drive nodes, to trigger a second quantum computation by the plurality of transmon qubits;
wherein each drive node and measuring entity in the plurality of control entities is synchronized with the central controller; and
wherein the second instruction is a conditional instruction that operates based on the measurement result of the first quantum computation.
2 . The computer-implemented method of claim 1 , wherein the set of selected channels being examined is a configurable subset of a plurality of channels.
3 . The computer-implemented method of claim 2 , wherein a channel select register provides a plurality of bits corresponding to each channel of the plurality of channels, each bit indicating whether the corresponding channel is required for resuming execution at the processing unit.
4 . The computer-implemented method of claim 1 , wherein data of the channel select register is stored in one or more built-in registers of the processing unit.
5 . The computer-implemented method of claim 1 , further comprising resuming execution by the processing unit after an occurrence of a timeout condition regardless of whether each channel of the set of selected channels has provided an input from a remote peer.
6 . The computer-implemented method of claim 5 , wherein the timeout condition is based on a configurable timeout value that is set by an instruction of the processing unit.
7 . The computer-implemented method of claim 6 , wherein the occurrence of the timeout condition is indicated by setting a bit in a condition register to allow a conditional jump to handle the timeout.
8 . The computer-implemented method of claim 6 , wherein the occurrence of the timeout condition is indicated by setting a bit in an error register that is polled by the processing unit.
9 . The computer-implemented method of claim 1 , wherein the inputs provided by the set of selected channels reside in a set of registers of the processing unit that can be queried.
10 . A computing device comprising:
a processing unit; and
a storage device storing a set of instructions, wherein an execution of the set of instructions by the processor configures the computing device to perform acts comprising:
executing a first instruction at a processing unit of a first computing device, wherein the processing unit implements a central controller that interconnects a plurality of drive nodes and measuring entities for respectively configuring and measuring a plurality of transmon qubits in a superconducting quantum computing system, wherein respective drive nodes are separate computing devices, and a measuring entity is a separate device to measure and readout multiple transmon qubits;
upon determining that the first instruction is a multi-channel-receive instruction:
stalling the processing unit from executing any further instructions until each channel of a set of selected channels has provided an input from a remote peer measuring entity, wherein different channels in the set of selected channels are examined simultaneously; and
resuming execution at the processing unit of a second instruction after the stalling; wherein each channel of the set of selected channels carries a measurement result for a first quantum computation by the plurality of transmon qubits from the measuring entity; wherein executing the second instruction causes the central controller to send a message, via the respective drive nodes, to trigger a second quantum computation by the plurality of transmon qubits; wherein each drive node and measuring entity in the plurality of control entities is synchronized with the central controller; and wherein the second instruction is a conditional instruction that operates based on the measurement result of the first quantum computation.
11 . A computer-implemented method comprising:
executing a first instruction at a processing unit of a first computing device, wherein the processing unit implements a central controller that interconnects a plurality of drive nodes and measuring entities for respectively configuring and measuring a plurality of transmon qubits in a superconducting quantum computing system, wherein respective drive nodes are separate computing devices, and a measuring entity is a separate device to measure and readout multiple transmon qubits;
upon determining that the first instruction is a start-to-receive instruction:
starting a set of selected channels to receive data from remote peers;
starting a timeout counter; and
proceeding to execute another instruction at the processing unit without stalling; and
upon determining that the first instruction is a wait-receive-or-timeout instruction:
stalling the processing unit from executing any further instructions until each channel of the set of selected channels has provided an input from a remote peer measuring entity or when the timeout counter indicates a timeout condition, wherein different channels in the set of selected channels are examined simultaneously; and
resuming execution at the processing unit of a second instruction after the stalling; wherein each channel of the set of selected channels carries a measurement result for a first quantum computation by the plurality of transmon qubits from the measuring entity; wherein executing the second instruction causes the central controller to send a message, via the respective drive nodes, to trigger a second quantum computation by the plurality of transmon qubits; wherein each drive node and measuring entity in the plurality of control entities is synchronized with the central controller; and wherein the second instruction is a conditional instruction that operates based on the measurement result of the first quantum computation.