Large-scale quantum computers will require quantum gate operations between widely separated qubits. A method for implementing such operations, known as quantum gate teleportation (QGT), requires only local operations, classical communication, and shared entanglement. We demonstrate QGT in a scalable architecture by deterministically teleporting a controlled-NOT (CNOT) gate between two qubits in spatially separated locations in an ion trap. The entanglement fidelity of our teleported CNOT is in the interval (0.845, 0.872) at the 95% confidence level. The implementation combines ion shuttling with individually addressed single-qubit rotations and detections, same- and mixed-species two-qubit gates, and real-time conditional operations, thereby demonstrating essential tools for scaling trapped-ion quantum computers combined in a single device.

Ferritin is a protein nano-cage that encapsulates minerals inside an 8 nm cavity. Previous band gap measurements on the native mineral, ferrihydrite, have reported gaps as low as 1.0 eV and as high as 2.5-3.5 eV. To resolve this discrepancy we have used optical absorption spectroscopy, a well-established technique for measuring both direct and indirect band gaps. Our studies included controls on the protein nano-cage, ferritin with the native ferrihydrite mineral, and ferritin with reconstituted ferrihydrite cores of different sizes. We report measurements of an indirect band gap for native ferritin of 2.140 ± 0.015 eV (579.7 nm), with a direct transition appearing at 3.053 ± 0.005 eV (406.1 nm). We also see evidence of a defect-related state having a binding energy of 0.220 ± 0.010 eV . Reconstituted ferrihydrite minerals of different sizes were also studied and showed band gap energies which increased with decreasing size due to quantum confinement effects. Molecules that interact with the surface of the mineral core also demonstrated a small influence following trends in ligand field theory, altering the native mineral's band gap up to 0.035 eV.

ARTICLE This journal isIron-containing ferritin has been used for light harvesting and as a photocatalyst. In this study, we test the hypothesis that changing the iron mineral core composition can alter the light harvesting and photocatalytic properties of ferritin, by co-depositing iron in the presence of halides or oxo-anions. This caused the anions to be incorporated into the iron mineral. We report that some of these new iron minerals possess different band gaps than the original ferrihydrite within ferritin. We found an increase in band gap of up to 0.288 eV or a decrease by as much as 0.104 eV, depending on the type of anion and amount of anions incorporated into the ferrihydrite mineral. ARTICLEThis journal is

We report correlation measurements on two 9 Be + ions that violate a chained Bell inequality obeyed by any local-realistic theory. The correlations can be modeled as derived from a mixture of a local-realistic probabilistic distribution and a distribution that violates the inequality. A statistical framework is formulated to quantify the local-realistic fraction allowable in the observed distribution without the fair-sampling or independent-and-identical-distributions assumptions. We exclude models of our experiment whose local-realistic fraction is above 0.327 at the 95 % confidence level. This bound is significantly lower than 0.586, the minimum fraction derived from a perfect ClauserHorne-Shimony-Holt inequality experiment. Furthermore, our data provides a device-independent certification of the deterministically created Bell states.Recently several groups have reported loophole-free tests of local realism with Bell's theorem [1], rejecting with high confidence theories of local realism [2][3][4]. While these experiments falsify the idea that nature obeys local realism, they are limited in the extent to which their data differs from local realism. Chained Bell inequality (CBI) [5] experiments can show greater departures from local realism in the following sense: Elitzur, Popescu, and Rohrlich [6] described a model of the distribution of outcomes measured from a quantum state as a mixture of a local-realistic distribution, which obeys Bell's inequalities, and another distribution that does not. Following their convention, we call these distributions "local" and "non-local." According to Ref. [6], a probability distribution P for the outcomes of an experiment can be written aswhere P L represents a local joint probability distribution (a "local part") and P N L represents a non-local distribution, with p local as the weight of the local component bound by 0 ≤ p local ≤ 1. For an ideal Clauser-HorneShimony-Holt (CHSH) Bell inequality experiment where two physical systems (usually particles) are jointly measured with four different measurement settings [7], the lowest attainable upper bound on the local content p local in any quantum distribution is ∼ 0.586 [8,9]. In principle, this bound can be lowered to zero by using a chained Bell inequality experiment.As indicated in Fig. 1.(a), CBI experiments are a generalization of a CHSH-type experiment. During each trial, a source that may be treated as a "black box" emits two systems labeled a and b, respectively. The experimentalist records the measurement outcomes after choosing a pair of measurements to perform separately on a and b. We use the symbols a k , b l to denote the respective measurement settings and a k b l for the pair. The latter is usually simply referred to as "the settings" or "the setting pairs". There is a hierarchy in which the Bell test SourceMeasurement:Illustration of a Bell inequality experiment. A source emits two systems a and b, here two 9 Be + ions. After choosing measurement settings a k and b l , the experiment implements Hilbert-space ...