F. Albarrán-Arriagada

Superconducting Circuit Architecture for Digital-Analog Quantum Computing

  1. J. Yu,
  2. J. C. Retamal,
  3. M. Sanz,
  4. E. Solano,
  5. and F. Albarrán-Arriagada
We propose a superconducting circuit architecture suitable for digital-analog quantum computing (DAQC) based on an enhanced NISQ family of nearest-neighbor interactions. DAQC makesa smart use of digital steps (single qubit rotations) and analog blocks (parametrized multiqubit operations) to outperform digital quantum computing algorithms. Our design comprises a chain of superconducting charge qubits coupled by superconducting quantum interference devices (SQUIDs). Using magnetic flux control, we can activate/deactivate exchange interactions, double excitation/de-excitations, and others. As a paradigmatic example, we present an efficient simulation of an ℓ×h fermion lattice (with 2<ℓ≤h), using only 2(2ℓ+1)2+24 analog blocks. The proposed architecture design is feasible in current experimental setups for quantum computing with superconducting circuits, opening the door to useful quantum advantage with fewer resources.[/expand]
arxiv pdf

One-way Quantum Computing in Superconducting Circuits

  1. F. Albarrán-Arriagada,
  2. G. Alvarado-Barrios,
  3. M. Sanz,
  4. G. Romero,
  5. L. Lamata,
  6. J. C. Retamal,
  7. and E. Solano
We propose a method for the implementation of one-way quantum computing in superconducting circuits. Measurement-based quantum computing is a universal quantum computation paradigm
in which an initial cluster-state provides the quantum resource, while the iteration of sequential measurements and local rotations encodes the quantum algorithm. Up to now, technical constraints have limited a scalable approach to this quantum computing alternative. The initial cluster state can be generated with available controlled-phase gates, while the quantum algorithm make use of high-fidelity readout and coherent feedback. With current technology, we estimate that quantum algorithms with above 20 qubits may be implemented in the path towards quantum supremacy. Moreover, we propose an alternative initial state with properties of maximal persistence and maximal connectedness, reducing the required resources of one-way quantum computing protocols.
arxiv pdf

Spin-1 models in the ultrastrong coupling regime of circuit QED

  1. F. Albarrán-Arriagada,
  2. L. Lamata,
  3. E. Solano,
  4. G. Romero,
  5. and J. C. Retamal
We propose a superconducting circuit platform for simulating spin-1 models. To this purpose we consider a chain of N ultrastrongly coupled qubit-resonator systems interacting through
a grounded SQUID. The anharmonic spectrum of the qubit-resonator system and the selection rules imposed by the global parity symmetry allow us to activate well controlled two-body quantum gates via AC-pulses applied to the SQUID. We show that our proposal has the same simulation time for any number of spin-1 interacting particles. This scheme may be implemented within the state-of-the-art circuit QED in the ultrastrong coupling regime.
arxiv pdf