نتایج جستجو برای: qubit

تعداد نتایج: 11810  

Journal: :Physical review letters 2013
Simon Gustavsson Olger Zwier Jonas Bylander Fei Yan Fumiki Yoshihara Yasunobu Nakamura Terry P Orlando William D Oliver

We present a new method for determining pulse imperfections and improving the single-gate fidelity in a superconducting qubit. By applying consecutive positive and negative π pulses, we amplify the qubit evolution due to microwave pulse distortions, which causes the qubit state to rotate around an axis perpendicular to the intended rotation axis. Measuring these rotations as a function of pulse...

2013
Peter Levay Michel Planat Metod Saniga Péter Lévay

We invoke some ideas from finite geometry to map bijectively 135 heptads of mutually commuting three-qubit observables into 135 symmetric four-qubit ones. After labeling the elements of the former set in terms of a seven-dimensional Clifford algebra, we present the bijective map and most pronounced actions of the associated symplectic group on both sets in explicit forms. This formalism is then...

Journal: :Quantum Information & Computation 2007
Jian-Ming Cai Zheng-Wei Zhou Guang-Can Guo

We investigate the properties of different levels of entanglement in graph states which correspond to connected graphs. Combining the operational definition of graph states and the postulates of entanglement measures, we prove that in connected graph states of N > 3 qubits there is no genuine three-qubit entanglement. For certain classes of graph states, all genuine k-qubit entanglement, 2 ≤ k ...

Journal: :Science 1999
Mooij Orlando Levitov Tian van der Wal CH Lloyd

A qubit was designed that can be fabricated with conventional electron beam lithography and is suited for integration into a large quantum computer. The qubit consists of a micrometer-sized loop with three or four Josephson junctions; the two qubit states have persistent currents of opposite direction. Quantum superpositions of these states are obtained by pulsed microwave modulation of the enc...

Journal: :Physical review letters 2016
Zijun Chen Julian Kelly Chris Quintana R Barends B Campbell Yu Chen B Chiaro A Dunsworth A G Fowler E Lucero E Jeffrey A Megrant J Mutus M Neeley C Neill P J J O'Malley P Roushan D Sank A Vainsencher J Wenner T C White A N Korotkov John M Martinis

Leakage errors occur when a quantum system leaves the two-level qubit subspace. Reducing these errors is critically important for quantum error correction to be viable. To quantify leakage errors, we use randomized benchmarking in conjunction with measurement of the leakage population. We characterize single qubit gates in a superconducting qubit, and by refining our use of derivative reduction...

Journal: :Physical review letters 2013
C M Quintana K D Petersson L W McFaul S J Srinivasan A A Houck J R Petta

We demonstrate quantum control and entanglement generation using a Landau-Zener beam splitter formed by coupling two transmon qubits to a superconducting cavity. Single passage through the cavity-mediated qubit-qubit avoided crossing provides a direct test of the Landau-Zener transition formula. Consecutive sweeps result in Landau-Zener-Stückelberg interference patterns, with a visibility that ...

Journal: :Physical review letters 2011
Y Kubo C Grezes A Dewes T Umeda J Isoya H Sumiya N Morishita H Abe S Onoda T Ohshima V Jacques A Dréau J-F Roch I Diniz A Auffeves D Vion D Esteve P Bertet

We report the experimental realization of a hybrid quantum circuit combining a superconducting qubit and an ensemble of electronic spins. The qubit, of the transmon type, is coherently coupled to the spin ensemble consisting of nitrogen-vacancy centers in a diamond crystal via a frequency-tunable superconducting resonator acting as a quantum bus. Using this circuit, we prepare a superposition o...

Journal: :Science 2004
Christian F Roos Mark Riebe Hartmut Häffner Wolfgang Hänsel Jan Benhelm Gavin P T Lancaster Christoph Becher Ferdinand Schmidt-Kaler Rainer Blatt

We report the deterministic creation of maximally entangled three-qubit states-specifically the Greenberger-Horne-Zeilinger (GHZ) state and the W state-with a trapped-ion quantum computer. We read out one of the qubits selectively and show how GHZ and W states are affected by this local measurement. Additionally, we demonstrate conditional operations controlled by the results from reading out o...

2005
Mário Ziman

We investigate decoherence channels that are modelled as a sequence of collisions of a quantum system (e.g., a qubit) with particles (e.g., qubits) of the environment. We show that collisions induce decoherence when a bi-partite interaction between the system qubit and an environment (reservoir) qubit is described by the controlled-U unitary transformation (gate). We characterize decoherence ch...

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