Characterizing quantum supremacy in near-term devices

  title={Characterizing quantum supremacy in near-term devices},
  author={Sergio Boixo and Sergei V. Isakov and Vadim N. Smelyanskiy and Ryan Babbush and Nan Ding and Zhang Jiang and Michael J. Bremner and John M. Martinis and Hartmut Neven},
  journal={Nature Physics},
A critical question for quantum computing in the near future is whether quantum devices without error correction can perform a well-defined computational task beyond the capabilities of supercomputers. Such a demonstration of what is referred to as quantum supremacy requires a reliable evaluation of the resources required to solve tasks with classical approaches. Here, we propose the task of sampling from the output distribution of random quantum circuits as a demonstration of quantum supremacy… 

Boundaries of quantum supremacy via random circuit sampling

The constraints of the observed quantum runtime advantage in an analytical extrapolation to circuits with a larger number of qubits and gates are examined, suggesting the boundaries of quantum supremacy via random circuit sampling may fortuitously coincide with the advent of scalable, error corrected quantum computing in the near term.

QAOA for Max-Cut requires hundreds of qubits for quantum speed-up

To lower bound the size of quantum computers with practical utility, realistic simulations of the Quantum Approximate Optimization Algorithm are performed and it is concluded that quantum speedup will not be attainable, at least for a representative combinatorial problem, until several hundreds of qubits are available.

Quantum supremacy with analog quantum processors for material science and machine learning

This work shows that the same sampling complexity can be achieved from driven analog quantum processors, with less stringent requirements for coherence and control, and proposes a novel variational hybrid quantum-classical approach, exploiting the system's inherent tunable MBL dynamics, to train the device to learn distributions of complex classical data.

Quantum advantage from energy measurements of many-body quantum systems

This work investigates whether quantum advantage demonstrations can be achieved for more physically-motivated sampling problems, related to measurements of physical observables, and describes a family of Hamiltonians with nearest-neighbour interactions on a 2D lattice that can be efficiently measured with high resolution using a quantum circuit of commuting gates.

Pareto-Efficient Quantum Circuit Simulation Using Tensor Contraction Deferral

It is shown that deferring tensor contractions can extend the boundaries of what can be computed on classical systems and can be used to simulate $7 \times 7$-qubit random circuits to arbitrary depth by leveraging secondary storage.

Scalable Evaluation of Quantum-Circuit Error Loss Using Clifford Sampling.

The quadratic error loss and the final-state fidelity loss are used to characterize quantum circuits and it is found that the distribution of computation error is approximately Gaussian, which justifies the quadratics error loss.

Quantum Supremacy Is Both Closer and Farther than It Appears

A massively-parallel simulation tool Rollright is developed that does not require inter-process communication (IPC) or proprietary hardware, and two ways to trade circuit fidelity for computational speedups are developed, so as to match the fidelity of a given quantum computer --- a task previously thought impossible.

Establishing the quantum supremacy frontier with a 281 Pflop/s simulation

HPC simulations of hard random quantum circuits (RQC), which have been recently used as a benchmark for the first experimental demonstration of quantum supremacy, sustaining an average performance of 281 Pflop/s on Summit, currently the fastest supercomputer in the world, are reported.

Quantum optimization using variational algorithms on near-term quantum devices

The quantum volume as a metric to compare the power of near-term quantum devices is discussed and simple error-mitigation schemes are introduced that could improve the accuracy of determining ground-state energies.

Quantum supremacy using a programmable superconducting processor

Quantum supremacy is demonstrated using a programmable superconducting processor known as Sycamore, taking approximately 200 seconds to sample one instance of a quantum circuit a million times, which would take a state-of-the-art supercomputer around ten thousand years to compute.



Complexity-Theoretic Foundations of Quantum Supremacy Experiments

General theoretical foundations are laid for how to use special-purpose quantum computers with 40--50 high-quality qubits to demonstrate "quantum supremacy": that is, a clear quantum speedup for some task, motivated by the goal of overturning the Extended Church-Turing Thesis as confidently as possible.

Achieving quantum supremacy with sparse and noisy commuting quantum computations

It is shown that purely classical error-correction techniques can be used to design IQP circuits which remain hard to simulate classically, even in the presence of arbitrary amounts of noise of this form.

Breaking the 49-Qubit Barrier in the Simulation of Quantum Circuits

With the current rate of progress in quantum computing technologies, systems with more than 50 qubits will soon become reality. Computing ideal quantum state amplitudes for devices of such and larger

Randomized Benchmarking of Quantum Gates

A key requirement for scalable quantum computing is that elementary quantum gates can be implemented with sufficiently low error. One method for determining the error behavior of a gate

Large-scale simulations of error prone quantum computation devices

This work assesses the power of error-prone quantum computation devices using largescale numerical simulations on parallel supercomputers and concludes that quantum error correction is especially well suited for the correction of operational imprecisions and systematic over-rotations.

State preservation by repetitive error detection in a superconducting quantum circuit

The protection of classical states from environmental bit-flip errors is reported and the suppression of these errors with increasing system size is demonstrated, motivating further research into the many challenges associated with building a large-scale superconducting quantum computer.

Superconducting quantum circuits at the surface code threshold for fault tolerance

The results demonstrate that Josephson quantum computing is a high-fidelity technology, with a clear path to scaling up to large-scale, fault-tolerant quantum circuits.

Simulation of low-depth quantum circuits as complex undirected graphical models

Near term quantum computers with a high quantity (around 50) and quality (around 0.995 fidelity for two-qubit gates) of qubits will approximately sample from certain probability distributions beyond

Logic gates at the surface code threshold: Superconducting qubits poised for fault-tolerant quantum computing

The results demonstrate that Josephson quantum computing is a high-fidelity technology, with a clear path to scaling up to large-scale, fault-tolerant quantum circuits.

Classical simulation of commuting quantum computations implies collapse of the polynomial hierarchy

  • M. BremnerR. JozsaD. Shepherd
  • Computer Science, Mathematics
    Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences
  • 2010
The class post-IQP of languages decided with bounded error by uniform families of IQP circuits with post-selection is introduced, and it is proved first that post- IQP equals the classical class PP, and that if the output distributions of uniform IQP circuit families could be classically efficiently sampled, then the infinite tower of classical complexity classes known as the polynomial hierarchy would collapse to its third level.