97 research outputs found
Quantum logic for control and manipulation of molecular ions using a frequency comb
Due to their rich level structure, molecules are well-suited for probing time
variation of fundamental constants, precisely measuring parity violation and
time-reversal non-invariance effects, studying quantum mechanical aspects of
chemical reactions, and implementing scalable quantum information processing
architectures. Molecular ions are particularly attractive for these
applications due to their long storage times and the near-perfect isolation
from environment that result in long coherence times required to achieve high
measurement precision and reduce systematic errors. However, the control of
molecular quantum states remains a challenge. Based on quantum logic
techniques, we propose a scheme for preparation, manipulation, and detection of
quantum states of single molecular ions. The scheme relies on coherent coupling
between internal and motional degrees of freedom of the molecular ion via a
frequency comb laser field, while detection and cooling of the motion of ions
is done via a co-trapped atomic ion.Comment: 5 pages, 3 figure
Quantum Teleportation Between Distant Matter Qubits
Quantum teleportation is the faithful transfer of quantum states between
systems, relying on the prior establishment of entanglement and using only
classical communication during the transmission. We report teleportation of
quantum information between atomic quantum memories separated by about 1 meter.
A quantum bit stored in a single trapped ytterbium ion (Yb+) is teleported to a
second Yb+ atom with an average fidelity of 90% over a replete set of states.
The teleportation protocol is based on the heralded entanglement of the atoms
through interference and detection of photons emitted from each atom and guided
through optical fibers. This scheme may be used for scalable quantum
computation and quantum communication.Comment: 5 pages, 4 figure
A heralded quantum gate between remote quantum memories
We demonstrate a probabilistic entangling quantum gate between two distant
trapped ytterbium ions. The gate is implemented between the hyperfine "clock"
state atomic qubits and mediated by the interference of two emitted photons
carrying frequency encoded qubits. Heralded by the coincidence detection of
these two photons, the gate has an average fidelity of 90+-2%. This entangling
gate together with single qubit operations is sufficient to generate large
entangled cluster states for scalable quantum computing
Bell inequality violation with two remote atomic qubits
We observe violation of a Bell inequality between the quantum states of two
remote Yb ions separated by a distance of about one meter with the detection
loophole closed. The heralded entanglement of two ions is established via
interference and joint detection of two emitted photons, whose polarization is
entangled with each ion. The entanglement of remote qubits is also
characterized by full quantum state tomography.Comment: 4 pages, 4 figure
Quantum state preparation and control of single molecular ions
Preparing molecules at rest and in a highly pure quantum state is a long
standing dream in chemistry and physics, so far achieved only for a select set
of molecules in dedicated experimental setups. Here, a quantum-limited
combination of mass spectrometry and Raman spectroscopy is proposed that should
be applicable to a wide range of molecular ions. Excitation of electrons in the
molecule followed by uncontrolled decay and branching into several lower energy
states is avoided. Instead, the molecule is always connected to rotational
states within the electronic and vibrational ground-state manifold, while a
co-trapped atomic ion provides efficient entropy removal and allows for
extraction of information on the molecule. The outlined techniques might enable
preparation, manipulation and measurement of a large multitude of molecular ion
species with the same instrument, with applications including, but not limited
to, precise determination of molecular properties and fundamental tests of
physics.Comment: 12 pages, 2 figures, reformatted for resubmissio
Quantum interference of electromagnetic fields from remote quantum memories
We observe quantum, Hong-Ou-Mandel, interference of fields produced by two
remote atomic memories. High-visibility interference is obtained by utilizing
the finite atomic memory time in four-photon delayed coincidence measurements.
Interference of fields from remote atomic memories is a crucial element in
protocols for scalable generation of multi-node remote qubit entanglement.Comment: 4 pages, 3 figure
Entanglement of remote atomic qubits
We report observations of entanglement of two remote atomic qubits, achieved
by generating an entangled state of an atomic qubit and a single photon at Site
A, transmitting the photon to Site B in an adjacent laboratory through an
optical fiber, and converting the photon into an atomic qubit. Entanglement of
the two remote atomic qubits is inferred by performing, locally, quantum state
transfer of each of the atomic qubits onto a photonic qubit and subsequent
measurement of polarization correlations in violation of the Bell inequality
|S| <2. We experimentally determine S =2.16 +/- 0.03. Entanglement of two
remote atomic qubits, each qubit consisting of two independent spin wave
excitations, and reversible, coherent transfer of entanglement between matter
and light, represent important advances in quantum information science.Comment: 5 pages, 3 figure
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