High harmonic generation can produce attosecond-long pulses of light, which are a useful probe physical processes that require extremely high time resolution. A new mathematical analysis shows how electron delocalization contributes to this emission in solid.

Abstract Controlling electron tunneling is of fundamental importance in the design and operation semiconductor nanostructures such as field effect transistors (FETs) quantum computing device architectures. The exponential sensitivity with distance requires precise fabrication techniques to engineer desired dimensions achieve appropriate resistances/tunnel rates. This particularly important for high fidelity spin readout qubit exchange Here, it shown by combining precision accurate atomistic...

We describe dynamics of spin and valley transitions driven by alternating electric fields in quantum dots defined electrostatically within semiconducting carbon nanotubes (CNT). use the tight-binding approach to states localized a dot taking into account circumferential spin-orbit interaction due $s\text{\ensuremath{-}}p$ hybridization external fields. The basis eigenstates is used solution time-dependent Schr\"odinger equation for description flips intervalley that are periodic perturbation...

Electrically addressing spin systems is predicted to be a key component in developing scalable semiconductor-based quantum-processing architectures, enable fast spin-qubit manipulation and long-distance entanglement via microwave photons. However, single spins have no electric dipole, therefore spin-orbit mechanism must integrated the qubit design. Here, we propose couple photons atomically precise donor devices silicon using hyperfine interaction intrinsic an electrically induced coupling....

We consider spin rotations in single- and two-electron quantum dots that are driven by an external ac electric field with two mechanisms couple the electron spatial motion degree of freedom: spin-orbit interaction a random fluctuation Overhauser due to nuclear bath. perform systematic numerical simulation system using finite-difference approach exact account taken for electron-electron correlation. The demonstrates oscillation fluctuating is translated into effective magnetic during wave...

Spin coupling of non-nearest-neighbor qubits is interest to enhance connectivity in quantum computing architectures. Solving and predicting many-body problems exactly computationally challenging, though, so the approach has remained largely unexplored. This study uses a full configuration-interaction technique combined with atomistic tight-binding calculations investigate exchange-coupling mechanism analogous superexchange magnetic materials. turn out be less susceptible charge noise than...

Phosphorus donor nuclear spins in silicon couple weakly to the environment, making them promising candidates for high-fidelity qubits. The state of a spin qubit can be manipulated and read out using its hyperfine interaction with electron confined by potential. Here we use master-equation-based approach investigate how backaction from this electron-mediated measurement affects lifetimes single multidonor We analyze process as function electric magnetic fields strength. Apart flips, identify...

The two-electron states and exchange couplings are investigated for a phosphorous donor pair in silicon using an atomistic full configuration interaction method separations spanning from 0.4 to 15 nm. Three distinct separation regimes appear our large basis calculations, which the validity of simplified methods such as Heitler-London Hartree-Fock type approaches can be assessed. For bulk donors, coupling saturates below 5 nm due excited bonding orbital contributions wave functions. Ionic...

Singlet-triplet qubits typically require large magnetic field gradients on the order of militeslas to achieve high-fidelity electrically-controlled qubit operations. However, such in quantum dot systems also increase charge noise and provide a relaxation pathway from triplet singlet state, making readout challenging. Recently, shelving latched have been employed gate-defined dots donor-dot fidelities 80% 99.86%, respectively. In this paper, we theoretically examine singlet-triplet techniques...

We consider photon-assisted tunneling (PAT) and the Landau--Zener--Stueckelberg (LZS) interference for double quantum dots induced electrostatically along a semiconducting carbon nanotube. An atomistic tight-binding approach time-dependent configuration-interaction method are employed to describe systems of few confined electrons holes. reproduce patterns LZS recently observed describing transport across hole-localized states. Moreover, we indicate that charge configurations which ground...

We consider electron states in n-p double quantum dots defined a semiconducting carbon nanotube (CNT) by an external potential. describe formation of extended single-electron orbitals originating from the conduction and valence bands confined minimum maximum potential, respectively. solve problem pair using exact diagonalization method within tight-binding approach, which allows for straightforward treatment band states, keeping account intervalley scattering mediated atomic defects...

An ambipolar n-p double quantum dot defined by potential variation along a semiconducting carbon-nanotube is considered.We focus on the (1e,1h) charge configuration with single excess electron in conduction band state confined n-type and missing valence of p-dot for which lifting Pauli blockade current was observed electric-dipole spin resonance [E. A. Laird et al.Nat.Nanotech.8 , 565 (2013)].The dynamics system driven periodic electric field studied Floquet theory timedependent interaction...

We develop an effective tight-binding Hamiltonian for spin-orbit (SO) interaction in bent carbon nanotubes (CNT) the electrons forming π bonds between nearest neighbor atoms.We account bend of CNT and intrinsic spinorbit which introduce mixing σ p z orbitals along CNT.The effect contributes to main origin SO coupling -the folding graphene plane into nanotube.We discuss bend-related contribution resonant single-electron spin charge transitions a double quantum dot.We report that although is...

We provide an atomistic tight-binding description of a few carriers confined in ambipolar (n-p) double quantum dots defined semiconducting carbon nanotube. focus our attention on the charge state system which Pauli blockade current flow is observed [F. Pei et al., Nat. Nanotechnol. 7, 630 (2012); E. A. Laird ibid 8, 565 (2013)] with single excess electron n-dot and hole p-dot. use configuration interaction approach to determine spin-valley structure states near neutrality point discuss its...

Atomic engineering in a solid-state material has the potential to functionalize host with novel phenomena. STM-based lithographic techniques have enabled placement of individual phosphorus atoms at selective lattice sites silicon atomic precision. Here, we show that by placing four donors spaced 10-15 nm apart from their neighbours linear chain, it is possible realize coherent spin coupling between end dopants analogous superexchange interaction magnetic materials. Since are promising...

Abstract Precision‐placed atom qubits in silicon offer a unique means to confine electrons and control their spins with extreme accuracy, which can be leveraged construct powerful quantum computers. To date have been successfully realized using hosted either on single phosphorus or multi‐donor dot. Here, novel molecular regime is explored are bound two donor dots separated by ≈8 nm natural substrate. The state, provided these spatially donors, used study exquisite precision the impact of...

Phosphorus donor nuclear spins in silicon couple weakly to the environment making them promising candidates for high-fidelity qubits. The state of a spin qubit can be manipulated and read out using its hyperfine interaction with electron confined by potential. Here we use master equation-based approach investigate how backaction from this electron-mediated measurement affects lifetimes single multi-donor We analyze process as function electric magnetic fields, strength. Apart flips, identify...

High harmonic generation, HHG, in solids is a delocalized process, which still intensely debated. Here, we develop model what connects the well-understood HHG atoms to delocalization problem of solids.

Electrically addressing spin systems is predicted to be a key component in developing scalable semiconductor-based quantum processing architectures, enable fast qubit manipulation and long-distance entanglement via microwave photons. However, single spins have no electric dipole, therefore spin-orbit mechanism must integrated the design. Here, we propose couple photons atomically precise donor devices silicon using hyperfine interaction intrinsic an electrically-induced coupling. We...