100 research outputs found
A few-electron quadruple quantum dot in a closed loop
We report the realization of a quadruple quantum dot device in a square-like
configuration where a single electron can be transferred on a closed path free
of other electrons. By studying the stability diagrams of this system, we
demonstrate that we are able to reach the few-electron regime and to control
the electronic population of each quantum dot with gate voltages. This allows
us to control the transfer of a single electron on a closed path inside the
quadruple dot system. This work opens the route towards electron spin
manipulation using spin-orbit interaction by moving an electron on complex
paths free of electron
A linear triple quantum dot system in isolated configuration
The scaling up of electron spin qubit based nanocircuits has remained
challenging up to date and involves the development of efficient charge control
strategies. Here we report on the experimental realization of a linear triple
quantum dot in a regime isolated from the reservoir. We show how this regime
can be reached with a fixed number of electrons. Charge stability diagrams of
the one, two and three electron configurations where only electron exchange
between the dots is allowed are observed. They are modelled with established
theory based on a capacitive model of the dot systems. The advantages of the
isolated regime with respect to experimental realizations of quantum simulators
and qubits are discussed. We envision that the results presented here will make
more manipulation schemes for existing qubit implementations possible and will
ultimately allow to increase the number of tunnel coupled quantum dots which
can be simultaneously controlled
Quantum manipulation of two-electron spin states in metastable double quantum dots
We studied experimentally the dynamics of the exchange interaction between
two antiparallel electron spins in a so-called metastable double quantum dot
where coupling to the electron reservoirs can be ignored. We demonstrate that
the level of control of such a double dot is higher than in conventional double
dots. In particular, it allows to couple coherently two electron spins in an
efficient manner following a scheme initially proposed by Loss and DiVincenzo.
The present study demonstrates that metastable quantum dots are a possible
route to increase the number of coherently coupled quantum dots.Comment: 5 pages, 4 figure
Magnetic dephasing in mesoscopic spin glasses
We have measured Universal Conductance Fluctuations in the metallic spin
glass Ag:Mn as a function of temperature and magnetic field. From this
measurement, we can access the phase coherence time of the electrons in the
spin glass. We show that this phase coherence time increases with both the
inverse of the temperature and the magnetic field. From this we deduce that
decoherence mechanisms are still active even deep in the spin glass phase
Experimental Test of the Numerical Renormalization Group Theory for Inelastic Scattering from Magnetic Impurities
We present measurements of the phase coherence time \tauphi in quasi
one-dimensional Au/Fe Kondo wires and compare the temperature dependence of
\tauphi with a recent theory of inelastic scattering from magnetic impurities
(Phys. Rev. Lett. 93, 107204 (2004)). A very good agreement is obtained for
temperatures down to 0.2 . Below the Kondo temperature , the inverse
of the phase coherence time varies linearly with temperature over almost one
decade in temperature.Comment: 5 pages, 3 figure
Observation of conduction electron spin resonance in boron doped diamond
We observe the electron spin resonance of conduction electrons in boron doped
(6400 ppm) superconducting diamond (Tc =3.8 K). We clearly identify the
benchmarks of conduction electron spin resonance (CESR): the nearly temperature
independent ESR signal intensity and its magnitude which is in good agreement
with that expected from the density of states through the Pauli
spin-susceptibility. The temperature dependent CESR linewidth weakly increases
with increasing temperature which can be understood in the framework of the
Elliott-Yafet theory of spin-relaxation. An anomalous and yet unexplained
relation is observed between the g-factor, CESR linewidth, and the resistivity
using the empirical Elliott-Yafet relation.Comment: 10 pages, 11 figures, submitted to Phys. Rev.
Injection of a single electron from static to moving quantum dots
We study the injection mechanism of a single electron from a static quantum
dot into a moving quantum dot created in a long depleted channel with surface
acoustic waves (SAWs). We demonstrate that such a process is characterized by
an activation law with a threshold that depends on the SAW amplitude and the
dot-channel potential gradient. By increasing sufficiently the SAW modulation
amplitude, we can reach a regime where the transfer is unitary and potentially
adiabatic. This study points at the relevant regime to use moving dots in
quantum information protocols.Comment: 5 pages, 4 figure
Efficient Radio Frequency filters for space constrained cryogenic set-ups
Noise filtering is an essential part for measurement of quantum phenomena at
extremely low temperatures. Here, we present the design of a filter which can
be installed in space constrained cryogenic environment containing a large
number of signal carrying lines. Our filters have a -3db point of 65kHz and its
performance at GHz frequencies are comparable to the best available RF filters.Comment: 9 pages, 4 figures, The capacitor reference in the first version was
wrong and has been changed to the right on
Piezoresistive Free‐standing Microfiber Strain Sensor for High‐resolution Battery Thickness Monitoring
Highly sensitive microfiber strain sensors are promising for the detection of mechanical deformations in applications where limited space is available. In particular for in situ battery thickness monitoring where high resolution and low detection limit are key requirements. Herein, the realization of a highly sensitive strain sensor for in situ lithium-ion (Li-ion) battery thickness monitoring is presented. The compliant fiber-shaped sensor is fabricated by an upscalable wet-spinning method employing a composite of microspherical core-shell conductive particles embedded in an elastomer. The electrical resistance of the sensor changes under applied strain, exhibiting a high strain sensitivity and extremely low strain detection limit of 0.00005 with high durability of 10 000 cycles. To demonstrate the accuracy and ease of applicability of this sensor, the real-time thickness change of a Li-ion battery pouch cell is monitored during the charge and discharge cycles. This work introduces a promising approach with the least material complexity for soft microfiber strain gauges
- …