The Experts below are selected from a list of 297 Experts worldwide ranked by ideXlab platform

Shou Zhang - One of the best experts on this subject based on the ideXlab platform.

  • one step construction of the multiple qubit rydberg controlled phase Gate
    Physical Review A, 2018
    Co-Authors: H Z Shen, Erjun Liang, Shou Zhang
    Abstract:

    Although the three-body Rydberg antiblockade regime (RABR) can produce Rabi oscillation between the Rydberg collective excited state and the collective ground state, it is still hard to use the RABR to construct the three-qubit Quantum Logic Gate in one step since the effective Hamiltonian is always accompanied by undesired Stark shifts. In order to overcome this difficulty, an additional laser is introduced to eliminate the Stark shifts in the ground-state subspace. And the initial RABR condition is modified to eliminate the remaining undesired Stark shifts in the collective-excitation subspace. The modified RABR is then generalized to the $n (ng3)$-qubit case. Based on the proposed regime, one-step schemes to construct three- and $n$-qubit Quantum controlled-PHASE Gates are proposed without the requirement of atomic addressability. The asymmetric Rydberg-Rydberg interaction, which is more practical for Rydberg atoms, is also discussed and proven to be feasible for the modified RABR and Quantum controlled-PHASE Gate in theory. A full-Hamiltonian-based master equation is used to evaluate the performance and some experimental parameters are also considered.

  • Fast Rydberg antiblockade regime and its applications in Quantum Logic Gates
    Physical Review A, 2017
    Co-Authors: Ya Gao, Erjun Liang, Shou Zhang
    Abstract:

    Unlike the Rydberg blockade regime, the Rydberg antiblockade regime (RABR) allows more than one Rydberg atom to be excited, which can bring other interesting phenomena and applications. We propose an alternative scheme to quickly achieve the RABR. The proposed RABR can be implemented by adjusting the detuning of the classical driving field, which is, in turn, based on the former numbers of the excited Rydberg atoms. In contrast to the former schemes, the current one enables more than two atoms to be excited to Rydberg states in a short period of time and thus is useful for large-scale Quantum information processing. The proposed RABR can be used to construct two- and multiqubit Quantum Logic Gates. In addition, a Rydberg excitation superatom, which can decrease the blockade error and enlarge the blockade radius for Rydberg blockade-based schemes, is constructed based on the suggested RABR and used to realize a more robust Quantum Logic Gate. The mechanical effect and the ionization are discussed, and the performance is investiGated using the master-equation method. Finally, other possible applications of the present RABR are also given.

Isaac L Chuang - One of the best experts on this subject based on the ideXlab platform.

  • demonstration of a Quantum Logic Gate in a cryogenic surface electrode ion trap
    APS, 2010
    Co-Authors: Shannon X Wang, Jaroslaw Labaziewicz, Ruth Shewmon, Isaac L Chuang
    Abstract:

    We demonstrate Quantum control techniques for a single trapped ion in a cryogenic, surface-electrode trap. A narrow optical transition of Sr{sup +} along with the ground and first excited motional states of the harmonic trapping potential form a two-qubit system. The optical qubit transition is susceptible to magnetic field fluctuations, which we stabilize with a simple and compact method using superconducting rings. Decoherence of the motional qubit is suppressed by the cryogenic environment. ac Stark shift correction is accomplished by controlling the laser phase in the pulse sequencer, eliminating the need for an additional laser. Quantum process tomography is implemented on atomic and motional states by use of conditional pulse sequences. With these techniques, we demonstrate a Cirac-Zoller controlled-not Gate in a single ion with a mean fidelity of 91(1)%.

  • methodology for Quantum Logic Gate construction
    Physical Review A, 2000
    Co-Authors: X Zhou, Debbie Leung, Isaac L Chuang
    Abstract:

    We present a general method to construct fault-tolerant Quantum Logic Gates with a simple primitive, which is an analog of Quantum teleportation. The technique extends previous results based on traditional Quantum teleportation @Gottesman and Chuang, Nature ~London! 402, 390 ~1999!# and leads to straightforward and systematic construction of many fault-tolerant encoded operations, including the p/8 and Toffoli Gates. The technique can also be applied to the construction of remote Quantum operations that cannot be directly performed.

  • Demonstration of Quantum Logic Gates in liquid crystal nuclear magnetic resonance
    The Journal of Chemical Physics, 2000
    Co-Authors: Małgorzata Marjańska, Isaac L Chuang, Mark G. Kubinec
    Abstract:

    1H–13C heteronuclear dipolar couplings are used to produce the NMR (nuclear magnetic resonance) version of a two bit controlled-NOT Quantum Logic Gate. This Gate is coupled with the Hadamard Gate to complete a circuit which generates the Einstein–Podolsky–Rosen (EPR) state which is the maximally entangled state of a pair of spins. The EPR state is crucial for the potential exponential speed advantage of Quantum computers over their classical counterparts. We sample the deviation density matrix of the two spin system to verify the presence of the EPR state. EPR state lifetimes are also measured with this technique, thereby demonstrating the viability of liquid crystals as a platform for Quantum computing.

Shi-biao Zheng - One of the best experts on this subject based on the ideXlab platform.

  • Quantum Logic Gates for Hot Ions without a Speed Limitation
    Physical review letters, 2003
    Co-Authors: Shi-biao Zheng
    Abstract:

    We propose a scheme for realizing two-qubit Quantum phase Gates with trapped ions in thermal motion. In the scheme, the ions are simultaneously illuminated by a standing-wave laser tuned to the carrier, which virtually excites several vibrational modes. The scheme puts no limitations on the intensity of the laser field, allowing the production of a Quantum Logic Gate for hot ions with an arbitrarily high speed as long as a laser field of sufficiently high intensity is available.

  • Simplified Quantum Logic Gates with trapped ions in thermal motion
    Optics Communications, 2000
    Co-Authors: Shi-biao Zheng
    Abstract:

    Abstract A simplified scheme is presented for realizing a two-bit Quantum Logic Gate in an ion trap. As the scheme of Sorensen and Molmer [Phys. Rev. Lett. 82 (1999) 1971], our scheme is insensitive to the interaction with the environment. However, the Quantum controlled-not Gate between two ions can

W M Itano - One of the best experts on this subject based on the ideXlab platform.

  • simplified motional heating rate measurements of trapped ions
    Physical Review A, 2007
    Co-Authors: R J Epstein, D. Leibfried, J Britton, S Seidelin, J H Wesenberg, John J Bollinger, Jason Amini, R B Blakestad, Jonathan Home, W M Itano
    Abstract:

    We have measured motional heating rates of trapped atomic ions, a factor that can influence multi-ion Quantum Logic Gate fidelities. Two simplified techniques were developed for this purpose: one relies on Raman sideband detection implemented with a single laser source, while the second is even simpler and is based on time-resolved fluorescence detection during Doppler recooling. We applied these methods to determine heating rates in a microfrabricated surface-electrode trap made of gold on fused quartz, which traps ions $40\phantom{\rule{0.3em}{0ex}}\mathrm{\ensuremath{\mu}}\mathrm{m}$ above its surface. Heating rates obtained from the two techniques were found to be in reasonable agreement. In addition, the trap gives rise to a heating rate of $300\ifmmode\pm\else\textpm\fi{}30\phantom{\rule{0.3em}{0ex}}{\mathrm{s}}^{\ensuremath{-}1}$ for a motional frequency of $5.25\phantom{\rule{0.3em}{0ex}}\mathrm{MHz}$, substantially below the trend observed in other traps.

  • experimental demonstration of a controlled not wave packet Gate
    Physical Review Letters, 2002
    Co-Authors: Brian Demarco, D. Leibfried, A Benkish, V Meyer, M A Rowe, B M Jelenkovic, W M Itano, J Britton, C Langer, T Rosenband
    Abstract:

    We report the experimental demonstration of a controlled-NOT (CNOT) Quantum Logic Gate between motional and internal-state qubits of a single ion where, as opposed to previously demonstrated Gates, the conditional dynamics depends on the extent of the ion's wave packet. Advantages of this CNOT Gate over one demonstrated previously are its immunity from Stark shifts due to off-resonant couplings and the fact that an auxiliary internal level is not required. We characterize the Gate Logic through measurements of the postGate ion state populations for both Logic basis and superposition input states, and we demonstrate the Gate coherence via an interferometric measurement.

John Chiaverini - One of the best experts on this subject based on the ideXlab platform.

  • distance scaling of electric field noise in a surface electrode ion trap
    Physical Review A, 2018
    Co-Authors: Jonathon Sedlacek, A Greene, Jules Stuart, Robert Mcconnell, Colin Bruzewicz, Jeremy M Sage, John Chiaverini
    Abstract:

    We investiGate anomalous ion-motional heating, a limitation to multi-qubit Quantum-Logic Gate fidelity in trapped-ion systems, as a function of ion-electrode separation. Using a multi-zone surface-electrode trap in which ions can be held at five discrete distances from the metal electrodes, we measure power-law dependencies of the electric-field noise experienced by the ion on the ion-electrode distance $d$. We find a scaling of approximately $d^{-4}$ regardless of whether the electrodes are at room temperature or cryogenic temperature, despite the fact that the heating rates are approximately two orders of magnitude smaller in the latter case. Through auxiliary measurements using application of noise to the electrodes, we rule out technical limitations to the measured heating rates and scalings. We also measure frequency scaling of the inherent electric-field noise close to $1/f$ at both temperatures. These measurements eliminate from consideration anomalous-heating models which do not have a $d^{-4}$ distance dependence, including several microscopic models of current interest.