Quantum 7, 966 (2023). https://doi.org/10.22331/q-2023-03-30-966 We study variational quantum algorithms from the perspective of free fermions. By deriving the explicit structure of the associated Lie algebras, we show that the Quantum Approximate Optimization Algorithm (QAOA) […]
Quantum 7, 965 (2023). https://doi.org/10.22331/q-2023-03-30-965 Thanks to common-mode noise rejection, differential configurations are crucial for realistic applications of phase and frequency estimation with atom interferometers. Currently, differential protocols with uncorrelated particles and mode-separable settings reach […]
Quantum 7, 964 (2023). https://doi.org/10.22331/q-2023-03-30-964 We develop and analyze a method for simulating quantum circuits on classical computers by representing quantum states as rooted tree tensor networks. Our algorithm first determines a suitable, fixed tree […]
Quantum 7, 963 (2023). https://doi.org/10.22331/q-2023-03-28-963 Semiclassically, laser pulses can be used to implement arbitrary transformations on atomic systems; quantum mechanically, residual atom-field entanglement spoils this promise. Transcoherent states are field states that fix this problem […]
Quantum 7, 962 (2023). https://doi.org/10.22331/q-2023-03-28-962 The implementation of time-evolution operators $U(t)$, called Hamiltonian simulation, is one of the most promising usage of quantum computers. For time-independent Hamiltonians, qubitization has recently established efficient realization of time-evolution […]
Quantum 7, 961 (2023). https://doi.org/10.22331/q-2023-03-23-961 We demonstrate an information erasure protocol that resets $N$ qubits at once. The method displays exceptional performances in terms of energy cost (it operates nearly at Landauer energy cost $kT […]
Quantum 7, 960 (2023). https://doi.org/10.22331/q-2023-03-23-960 The fidelity susceptibility is a tool for studying quantum phase transitions in the Hermitian condensed matter systems. Recently, it has been generalized with the biorthogonal basis for the non-Hermitian quantum […]
Quantum 7, 959 (2023). https://doi.org/10.22331/q-2023-03-23-959 One of the challenges of quantum computers in the near- and mid- term is the limited number of qubits we can use for computations. Finding methods that achieve useful quantum […]
Quantum 7, 958 (2023). https://doi.org/10.22331/q-2023-03-20-958 Field mediated entanglement experiments probe the quantum superposition of macroscopically distinct field configurations. We show that this phenomenon can be described by using a transparent quantum field theoretical formulation of […]
Quantum 7, 957 (2023). https://doi.org/10.22331/q-2023-03-20-957 Isometry operations encode the quantum information of the input system to a larger output system, while the corresponding decoding operation would be an inverse operation of the encoding isometry operation. […]
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