System and method of optimizing instructions for quantum computers

A quantum computing system includes a quantum processor having a plurality of qubits, a classical memory, and a classical processor. The classical processor is configured to compile a quantum program into logical assembly instructions in an intermediate language, aggregate the logical assembly instructions together into a plurality of logical blocks of instructions, generate a logical schedule for the quantum program based on commutativity between the plurality of logical blocks, generate a tentative physical schedule based on the logical schedule, the tentative physical schedule includes a mapping of the logical assembly instructions in the logical schedule onto the plurality of qubits of the quantum processor, aggregate instructions together within the tentative physical schedule that do not reduce parallelism, thereby generating an updated physical schedule; generate optimized control pulses for the aggregated instructions, and execute the quantum program on the quantum processor with the optimized control pulses and the updated physical schedule.A quantum computing system includes a quantum processor having a plurality of qubits, a classical memory, and a classical processor. The classical processor is configured to compile a quantum program into logical assembly instructions in an intermediate language, aggregate the logical assembly instructions together into a plurality of logical blocks of instructions, generate a logical schedule for the quantum program based on commutativity between the plurality of logical blocks, generate a tentative physical schedule based on the logical schedule, the tentative physical schedule includes a mapping of the logical assembly instructions in the logical schedule onto the plurality of qubits of the quantum processor, aggregate instructions together within the tentative physical schedule that do not reduce parallelism, thereby generating an updated physical schedule; generate optimized control pulses for the aggregated instructions, and execute the quantum program on the quantum processor with the optimized control pulses and the updated physical schedule.

Sep 12, 20190 citations

System and Method of Partial Compilation With Variational Algorithms for Quantum Computers

Frederic T. Chong, Pranav Gokhale, Yongshan Ding +1 more

A computing system includes a quantum processor with qubits, a classical memory including a quantum program defining a plurality of instructions in a source language, and a classical processor configured to: (i) receive a circuit of gates representing a quantum program for a variational algorithm in which computation is interleaved with compilation; (ii) identify a plurality of blocks, each block includes a subcircuit of gates, leaving one or more remainder subcircuits of the circuit of gates outside of the plurality of blocks; (iii) pre-compile each block of the plurality of blocks with a pulse generation program to generate a plurality of pre-compiled blocks including control pulses configured to perform the associated block on the quantum processor; and (iv) iteratively execute the quantum program using the pre-compiled blocks as static during runtime and recompiling the one or more remainder subcircuits on the classical processor at each iteration of execution.A computing system includes a quantum processor with qubits, a classical memory including a quantum program defining a plurality of instructions in a source language, and a classical processor configured to: (i) receive a circuit of gates representing a quantum program for a variational algorithm in which computation is interleaved with compilation; (ii) identify a plurality of blocks, each block includes a subcircuit of gates, leaving one or more remainder subcircuits of the circuit of gates outside of the plurality of blocks; (iii) pre-compile each block of the plurality of blocks with a pulse generation program to generate a plurality of pre-compiled blocks including control pulses configured to perform the associated block on the quantum processor; and (iv) iteratively execute the quantum program using the pre-compiled blocks as static during runtime and recompiling the one or more remainder subcircuits on the classical processor at each iteration of execution.

Sep 9, 20200 citations

Accelerated pattern matching method on a quantum computing system

Pradeep Niroula

A method of determining a pattern in a sequence of bits using a quantum computing system includes setting a first register of a quantum processor in a superposition of a plurality of string index states, encoding a bit string in a second register of the quantum processor, encoding a bit pattern in a third register of the quantum processor, circularly shifting qubits of the second register conditioned on the first register, amplifying an amplitude of a state combined with the first register in which the circularly shifted qubits of the second register matches qubits of the third register, measuring an amplitude of the first register and determining a string index state of the plurality of string index states associated with the amplified state, and outputting, by use of a classical computer, a string index associated with the first register in the measured state.A method of determining a pattern in a sequence of bits using a quantum computing system includes setting a first register of a quantum processor in a superposition of a plurality of string index states, encoding a bit string in a second register of the quantum processor, encoding a bit pattern in a third register of the quantum processor, circularly shifting qubits of the second register conditioned on the first register, amplifying an amplitude of a state combined with the first register in which the circularly shifted qubits of the second register matches qubits of the third register, measuring an amplitude of the first register and determining a string index state of the plurality of string index states associated with the amplified state, and outputting, by use of a classical computer, a string index associated with the first register in the measured state.

Mar 18, 20240 citations

Optimized Compilation of Aggregated Instructions for Realistic Quantum Computers

Yunong Shi, Nelson Leung, Pranav Gokhale +4 more

Recent developments in engineering and algorithms have made real-world applications in quantum computing possible in the near future. Existing quantum programming languages and compilers use a quantum assembly language composed of 1- and 2-qubit (quantum bit) gates. Quantum compiler frameworks translate this quantum assembly to electric signals (called control pulses) that implement the specified computation on specific physical devices. However, there is a mismatch between the operations defined by the 1- and 2-qubit logical ISA and their underlying physical implementation, so the current practice of directly translating logical instructions into control pulses results in inefficient, high-latency programs. To address this inefficiency, we propose a universal quantum compilation methodology that aggregates multiple logical operations into larger units that manipulate up to 10 qubits at a time. Our methodology then optimizes these aggregates by (1) finding commutative intermediate operations that result in more efficient schedules and (2) creating custom control pulses optimized for the aggregate (instead of individual 1- and 2-qubit operations). Compared to the standard gate-based compilation, the proposed approach realizes a deeper vertical integration of high-level quantum software and low-level, physical quantum hardware. We evaluate our approach on important near-term quantum applications on simulations of superconducting quantum architectures. Our proposed approach provides a mean speedup of $5\times$ , with a maximum of $10\times$ . Because latency directly affects the feasibility of quantum computation, our results not only improve performance but also have the potential to enable quantum computation sooner than otherwise possible.Recent developments in engineering and algorithms have made real-world applications in quantum computing possible in the near future. Existing quantum programming languages and compilers use a quantum assembly language composed of 1- and 2-qubit (quantum bit) gates. Quantum compiler frameworks translate this quantum assembly to electric signals (called control pulses) that implement the specified computation on specific physical devices. However, there is a mismatch between the operations defined by the 1- and 2-qubit logical ISA and their underlying physical implementation, so the current practice of directly translating logical instructions into control pulses results in inefficient, high-latency programs. To address this inefficiency, we propose a universal quantum compilation methodology that aggregates multiple logical operations into larger units that manipulate up to 10 qubits at a time. Our methodology then optimizes these aggregates by (1) finding commutative intermediate operations that result in more efficient schedules and (2) creating custom control pulses optimized for the aggregate (instead of individual 1- and 2-qubit operations). Compared to the standard gate-based compilation, the proposed approach realizes a deeper vertical integration of high-level quantum software and low-level, physical quantum hardware. We evaluate our approach on important near-term quantum applications on simulations of superconducting quantum architectures. Our proposed approach provides a mean speedup of $5\times$, with a maximum of $10\times$. Because latency directly affects the feasibility of quantum computation, our results not only improve performance but also have the potential to enable quantum computation sooner than otherwise possible.

arXiv:1902.01474International Conference on Architectural Support for Programming Languages and Operating Systems (ASPLOS)Apr 4, 2019118 citations

Quantum Computer Architecture: Towards Full-Stack Quantum Accelerators

Koen Bertels, Aritra Sarkar, Thomas Hubregtsen +5 more

This paper presents the definition and implementation of a quantum computer architecture to enable creating a new computational device - a quantum computer as an accelerator. A key question addressed is what such a quantum computer is and how it relates to the classical processor that controls the entire execution process. In this paper, we present explicitly the idea of a quantum accelerator which contains the full stack of the layers of an accelerator. Such a stack starts at the highest level describing the target application of the accelerator. The next layer abstracts the quantum logic outlining the algorithm that is to be executed on the quantum accelerator. In our case, the logic is expressed in the universal quantum-classical hybrid computation language developed in the group, called OpenQL, which visualised the quantum processor as a computational accelerator. The OpenQL compiler translates the program to a common assembly language, called cQASM, which can be executed on a quantum simulator. The cQASM represents the instruction set that can be executed by the micro-architecture implemented in the quantum accelerator. We propose that the industrial and societal application developers use perfect qubits that have no decoherence or error-rates. The perfect qubits offers facilities to the quantum application developer and they are not blocked by issues such as decoherence.This paper presents the definition and implementation of a quantum computer architecture to enable creating a new computational device - a quantum computer as an accelerator. A key question addressed is what such a quantum computer is and how it relates to the classical processor that controls the entire execution process. In this paper, we present explicitly the idea of a quantum accelerator which contains the full stack of the layers of an accelerator. Such a stack starts at the highest level describing the target application of the accelerator. The next layer abstracts the quantum logic outlining the algorithm that is to be executed on the quantum accelerator. In our case, the logic is expressed in the universal quantum-classical hybrid computation language developed in the group, called OpenQL, which visualised the quantum processor as a computational accelerator. The OpenQL compiler translates the program to a common assembly language, called cQASM, which can be executed on a quantum simulator. The cQASM represents the instruction set that can be executed by the micro-architecture implemented in the quantum accelerator. We propose that the industrial and societal application developers use perfect qubits that have no decoherence or error-rates. The perfect qubits offers facilities to the quantum application developer and they are not blocked by issues such as decoherence.

arXiv:1903.09575Design, Automation, and Test in EuropeMar 1, 202048 citations

Quantum computing using chiral qubits

Dmitri E. Kharzeev

An apparatus for performing quantum computing includes multiple qubits, each of at least a subset of the qubits comprising a loop formed of a Dirac or Weyl semimetal and having at least two stable quantum states. The apparatus further includes at least one terahertz cavity coupled with the qubits, the terahertz cavity being configured to detect the quantum states of the qubits. Each of at least the subset of qubits is configured to receive a circularly polarized radiation source. The radiation source is adapted to excite a chiral current in each of at least the subset of qubits, the quantum states of the plurality of qubits being a function of the chiral current.An apparatus for performing quantum computing includes multiple qubits, each of at least a subset of the qubits comprising a loop formed of a Dirac or Weyl semimetal and having at least two stable quantum states. The apparatus further includes at least one terahertz cavity coupled with the qubits, the terahertz cavity being configured to detect the quantum states of the qubits. Each of at least the subset of qubits is configured to receive a circularly polarized radiation source. The radiation source is adapted to excite a chiral current in each of at least the subset of qubits, the quantum states of the plurality of qubits being a function of the chiral current.

Apr 27, 20231 citation

5\times

, with a maximum of

10\times

. Because latency directly affects the feasibility of quantum computation, our results not only improve performance but also have the potential to enable quantum computation sooner than otherwise possible.