Themed collection Quantum Computing and Quantum Information Storage
Quantum computing and quantum information storage
This themed collection includes a selection of articles on quantum computing and quantum information storage.
Trapping Ca+ inside a molecular cavity: computational study of the potential energy surfaces for Ca+-[n]cycloparaphenylene, n = 5–12
Ion trap quantum computing utilizes electronic states of atomic ions such as Ca+ to encode information on to a qubit.
A theoretical study on laser cooling feasibility of XH (X = As, Sb and Bi): effects of intersystem crossings and spin–orbit couplings
The present calculations reveal the effects of intersystem crossings and spin–orbit couplings on laser cooling of the group VA hydrides, with an empirical law of “crossing point shifting down” down a group in the periodic table generalized.
Shannon and von Neumann entropies of multi-qubit Schrödinger's cat states
Cat state entropies for n = 2, 5, 10, and 15 qubits, as functions of qubit accuracies a and b.
Full-dimensional Schrödinger wavefunction calculations using tensors and quantum computers: the Cartesian component-separated approach
Traditional quantum chemistry is based on separability by particle. Here, we explore a radically different approach, based on separability by Cartesian component.
Molecular excited state calculations with adaptive wavefunctions on a quantum eigensolver emulation: reducing circuit depth and separating spin states
Using adaptive wavefunctions and spin restrictions to compute excited state energies of LiH in a VQE emulation greatly reduces ansatz depth, showing promise as a routine for molecular excited state calculations on near-term quantum computers.
Toward multifunctional molecular cells for quantum cellular automata: exploitation of interconnected charge and spin degrees of freedom
We discuss a possibility of using mixed-valence dimers comprising paramagnetic metal ions as molecular cells for quantum cellular automata. Charge distributions in these systems encode binary information with additional option of spin switching.
Understanding the magnetization blocking mechanism in N23−-radical-bridged dilanthanide single-molecule magnets
Two blocking energy barriers observed experimentally are confirmed by ab initio calculations. The blocking energy barrier of the Tb complexes that is approximately twice as large as that of the Dy analogues is explained.
Local spin and open quantum systems: clarifying misconceptions, unifying approaches
The theory of open quantum systems (OQSs) is applied to partition the squared spin operator into fragment (local spin) and interfragment (spin-coupling) contributions in a molecular system.
Bell inequalities for entangled qubits: quantitative tests of quantum character and nonlocality on quantum computers
Linear combination S of spin-projection correlation functions in the Clauser–Horne–Shimony–Holt inequality, from runs on an IBM quantum computer, after error mitigation. Values of S > 2 rule out local hidden-variable theories.
Magnetic anisotropy in YbIII complex candidates for molecular qubits: a theoretical analysis
The magnetic properties of mononuclear YbIII complexes have been explored by using multiconfigurational CASPT2/RASSI calculations.
Entanglement via rotational blockade of MgF molecules in a magic potential
Rotations of MgF molecules can be entangled via strong dipole–dipole interactions when trapped in optical tweezers with a magic polarization angle.
Surface chemical trapping of optical cycling centers
Quantum information processors are proposed, based on optical cycling centers trapped attached to a surface.
Magnetic properties and quench dynamics of two interacting ultracold molecules in a trap
The interplay of external fields and internal structure of two interacting ultracold trapped molecules produces rich magnetization diagrams and nonequilibrium dynamics.
Coherent manipulation of the internal state of ultracold 87Rb133Cs molecules with multiple microwave fields
We explore coherent multi-photon processes in 87Rb133Cs molecules using 3-level lambda and ladder configurations of rotational and hyperfine states, and discuss their relevance to future applications in quantum computation and quantum simulation.
Electromagnetic control of spin ordered Mn3 qubits: a density functional study
As expected from experiment, the [Mn3O(O2CMe)dpd3/2]2 dimer exists in an S = 12 ferromagnetic state. However the monomeric building blocks regardless of termination, are found in antiferromagnetic state with unusual local moments (S = 1).
Vacancies in graphene: an application of adiabatic quantum optimization
Interactions that dominate carbon-vacancy interchange were modeled on a quantum annealer. The method exploits the ground state and the excited states to extract the possible arrangements of vacancies in graphene and their relative formation energies.
Towards accurate prediction for laser-coolable molecules: relativistic coupled-cluster calculations for yttrium monoxide and prospects for improving its laser cooling efficiencies
Benchmark relativistic coupled-cluster calculations for yttrium monoxide (YO) with accurate treatment of relativistic and electron correlation effects are reported.
Solving complex eigenvalue problems on a quantum annealer with applications to quantum scattering resonances
The Quantum Annealer Eigensolver (QAE) is applied to the calculation of quantum scattering resonances and their lifetimes on a D-Wave quantum annealer.
Spin-momentum entanglement in a Bose–Einstein condensate
Mechanisms including two types of Raman laser coupling (Ω1 & Ω2) and rf field coupling (Ωrf) are applied to drive transitions between different hyperfine spin states. We investigated the entanglement between the spin and momentum degrees of freedom.
Quantum algorithm for simulating molecular vibrational excitations
We introduce a quantum algorithm for simulating molecular vibrational excitations during vibronic transitions. The algorithm is used to simulate vibrational excitations of pyrrole and butane during photochemical and mechanochemical excitations.
First-principles studies of strongly correlated states in defect spin qubits in diamond
Using a recently developed quantum embedding theory, we present first principles calculations of strongly correlated states of spin defects in diamond.
Dipole–phonon quantum logic with alkaline-earth monoxide and monosulfide cations
We outline a path towards universal quantum computation using the dipole–phonon interaction of polar molecular ions in an ion trap.
Protocol for optically pumping AlH+ to a pure quantum state
Three laser fields drive the population of AlH+ to a single hyperfine state.
Quantum simulation of electronic structure with a transcorrelated Hamiltonian: improved accuracy with a smaller footprint on the quantum computer
Molecular quantum computing simulations are currently limited by the use of minimal Gaussian bases, a problem we overcome using a canonical transcorrelated Hamiltonian to accelerate basis convergence, with unitary coupled cluster as an example.
From megahertz to terahertz qubits encoded in molecular ions: theoretical analysis of dipole-forbidden spectroscopic transitions in N2+
Theoretical study of the implementation of qubits and clock transitions in the spin, rotational, and vibrational degrees of freedom of molecular nitrogen ions including the effect of magnetic fields.
Quantum computation of silicon electronic band structure
We present minimal depth circuits implementing the variational quantum eigensolver algorithm and successfully use it to compute the band structure of silicon on a quantum machine for the first time.
Electrically tuned hyperfine spectrum in neutral Tb(II)(CpiPr5)2 single-molecule magnet
A strong Fermi contact (FC)-driven and electrically tunable hyperfine interaction is predicted for the neutral Tb(II)(CpiPr5)2 single-molecule magnet.
Nondestructive dispersive imaging of rotationally excited ultracold molecules
The setup for polarization-based dispersive imaging of molecules that relies on the intrinsic anistropy of their excited states to generate optical birefringence.
In search of molecular ions for optical cycling: a difficult road
Optical cycling, a continuous photon scattering off atoms or molecules, is the key tool in quantum information science.
On the order problem in construction of unitary operators for the variational quantum eigensolver
We propose an approach based on the Lie algebra – Lie group connection that reduces the order dependence in unitary transformations used in quantum computing.
About this collection
Quantum computing and information storage promise to revolutionize our information technology. Some basic theory of quantum computing has been established over the past two decades and researchers are on the cusp of quantum supremacy for truly useful systems. Yet, for quantum computing to become a reality we need to find a practical physical platform for realizing qubits with enough fidelity and depth to solve important problems. At present it is not clear what platform will succeed at this.
This topical collection will highlight physical chemistry/chemical physics aspects of quantum computing and quantum information storage and will welcome contributions from experimental and theoretical communities working on atomic, molecular, and optical aspects of emerging quantum information technology.
Guest Edited by: John Doyle (Harvard University, USA), Anna Krylov, (University of Southern California, USA) and Kang-Kuen Ni (Harvard University, USA)