Quantum Information and Computation for Chemistry

Kais, Sabre

doi:10.1002/9781118742631

Cited by 70 publications

(13 citation statements)

References 99 publications

(118 reference statements)

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“…Further applications of coherence and asymmetry quantifiers to detecting quantum phase transitions in fermionic and spin models have been reported in (Chen et al, 2016b;Li and Lin, 2016).…”

Section: G Quantum Phase Transitionsmentioning

confidence: 99%

Colloquium: Quantum coherence as a resource

2017

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The coherent superposition of states, in combination with the quantization of observables, represents one of the most fundamental features that mark the departure of quantum mechanics from the classical realm. Quantum coherence in many-body systems embodies the essence of entanglement and is an essential ingredient for a plethora of physical phenomena in quantum optics, quantum information, solid state physics, and nanoscale thermodynamics. In recent years, research on the presence and functional role of quantum coherence in biological systems has also attracted a considerable interest. Despite the fundamental importance of quantum coherence, the development of a rigorous theory of quantum coherence as a physical resource has only been initiated recently. In this Colloquium we discuss and review the development of this rapidly growing research field that encompasses the characterization, quantification, manipulation, dynamical evolution, and operational application of quantum coherence. Section II Resource Theories PIO Section IV Dynamics Section III Quantification Section V Applications ? ✓ Quantum Coherence incoherent operation coherent incoherent entangled S:A A S

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“…Further applications of coherence and asymmetry quantifiers to detecting quantum phase transitions in fermionic and spin models have been reported in (Chen et al, 2016b;Li and Lin, 2016).…”

Section: G Quantum Phase Transitionsmentioning

confidence: 99%

Colloquium: Quantum coherence as a resource

2017

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“…In ion traps, crosstalk is caused by residual illumination of laser light on neighbouring ions when applying single-and two-qubit gates. This error source can be effectively minimised for single-qubit gates [6] using composite pulse sequences and dynamical decoupling techniques [72] but becomes a more delicate issue when arising in the context of twoqubit entangling gates. With the use of carefully constructed pulse sequences, it is possible to suppress unwanted couplings on multi-qubit coupling operations, as shown in [73,74].…”

Section: Introductionmentioning

confidence: 99%

“…Generally, one can attempt to mitigate errors in the whole computation at different levels, such as at the level of gates [77,[81][82][83][84][85], circuits [62][63][64], full QECCs [53], or even entire algorithms [72,76]. Recent work [70] has described how to combat crosstalk in ion traps on the level of QECCs and circuits by choosing the arrangement of qubits in the QECC circuitry to minimise the fault-tolerant breaking effects of crosstalk, and by comparing the performance of different QECCs in the compass-code QEC family.…”

Section: Introductionmentioning

confidence: 99%

Crosstalk Suppression for Fault-tolerant Quantum Error Correction with Trapped Ions

Parrado-Rodríguez

Ryan-Anderson

Bermúdez

et al. 2021

Quantum

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Physical qubits in experimental quantum information processors are inevitably exposed to different sources of noise and imperfections, which lead to errors that typically accumulate hindering our ability to perform long computations reliably. Progress towards scalable and robust quantum computation relies on exploiting quantum error correction (QEC) to actively battle these undesired effects. In this work, we present a comprehensive study of crosstalk errors in a quantum-computing architecture based on a single string of ions confined by a radio-frequency trap, and manipulated by individually-addressed laser beams. This type of errors affects spectator qubits that, ideally, should remain unaltered during the application of single- and two-qubit quantum gates addressed at a different set of active qubits. We microscopically model crosstalk errors from first principles and present a detailed study showing the importance of using a coherent vs incoherent error modelling and, moreover, discuss strategies to actively suppress this crosstalk at the gate level. Finally, we study the impact of residual crosstalk errors on the performance of fault-tolerant QEC numerically, identifying the experimental target values that need to be achieved in near-term trapped-ion experiments to reach the break-even point for beneficial QEC with low-distance topological codes.

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“…We describe the mechanical environments using the model of [57], in which the Born-Markov master equations of two coupled nonidentical harmonic oscillators for the CB/SB cases are derived, starting from the following Hamiltonians. In the SB case each mechanical oscillator is coupled to its own reservoir, so there are two different baths described by: = + + (ˆˆ) [16,17,38,39,[41][42][43][44]. Notice that we have included a factor two in equation (4) to enforce an equal energy damping rate for both models: in SB case two independent channels dissipate, in CB case only one coordinate (center of mass) dissipates, but it is coupled to the bath with double strength 2l.…”

Section: Hamiltonian Modelmentioning

confidence: 99%

“…The particular dissipation scenario influences deeply the system. While SB dissipation usually destroys quantum correlations [38], dissipation in a CB leads to different results and enables phenomena such as decoherence free/noiseless subspaces [39], dark states [40], superradiance [38,41], dissipation-induced synchronization of linear networks of quantum harmonic oscillators [16,18] and of non-interacting spins [22], or no sudden-death of entanglement in systems of decoupled oscillators [42,43], that would not be present in these systems for SB dissipation. CB dissipation was first considered in the context of superradiance of atoms at distances smaller than the emitted radiation wavelength [41] and often assumed to arise when the spatial extension of a system is smaller than the correlation length of the structured bath.…”

Section: Introductionmentioning

confidence: 99%

Dynamical and quantum effects of collective dissipation in optomechanical systems

2017

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Optomechanical devices have been cooled to ground-state and genuine quantum features, as well as long-predicted nonlinear phenomena, have been observed. When packing close enough more than one optomechanical unit in the same substrate the question arises as to whether collective or independent dissipation channels are the correct description of the system. Here we explore the effects arising when introducing dissipative couplings between mechanical degrees of freedom. We investigate synchronization, entanglement and cooling, finding that collective dissipation can drive synchronization even in the absence of mechanical direct coupling, and allow to attain larger entanglement and optomechanical cooling. The mechanisms responsible for these enhancements are explored and provide a full and consistent picture.

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Quantum Information and Computation for Chemistry

Cited by 70 publications

References 99 publications

Colloquium: Quantum coherence as a resource

Colloquium: Quantum coherence as a resource

Crosstalk Suppression for Fault-tolerant Quantum Error Correction with Trapped Ions

Dynamical and quantum effects of collective dissipation in optomechanical systems

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