Steve Campbell

Dr. Steve Campbell

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Research Focus & Metrics

Academic Career Length

18Years (2009-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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12 October 2017 in Journal of Physics A: Mathematical and Theoretical
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Sebastian DeffnerSebastian Deffner
Sebastian Deffner
SCSteve Campbell
Steve Campbell
One of the most widely known building blocks of modern physics is Heisenberg’s indeterminacy principle. Among the different statements of this fundamental property of the full quantum mechanical nature of physical reality, the uncertainty relation for energy and time has a special place. Its interpretation and its consequences have inspired continued research efforts for almost a century. In its modern formulation, the uncertainty relation is understood as setting a fundamental bound on how fast any quantum system can evolve. In this topical review we describe important milestones, such as the Mandelstam–Tamm and the Margolus–Levitin bounds on the quantum speed limit , and summarise recent applications in a variety of current research fields—including quantum information theory, quantum computing, and quantum thermodynamics amongst several others. To bring order and to provide an access point into the many different notions and concepts, we have grouped the various approaches into the minimal time approach and the geometric approach , where the former relies on quantum control theory, and the latter arises from measuring the distinguishability of quantum states. Due to the volume of the literature, this topical review can only present a snapshot of the current state-of-the-art and can never be fully comprehensive. Therefore, we highlight but a few works hoping that our selection can serve as a representative starting point for the interested reader.

8 March 2017 in Physical Review Letters
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SCSteve Campbell
Steve Campbell
Sebastian DeffnerSebastian Deffner
Sebastian Deffner
Achieving effectively adiabatic dynamics is a ubiquitous goal in almost all areas of quantum physics. Here, we study the speed with which a quantum system can be driven when employing transitionless quantum driving. As a main result, we establish a rigorous link between this speed, the quantum speed limit, and the (energetic) cost of implementing such a shortcut to adiabaticity. Interestingly, this link elucidates a trade-off between speed and cost, namely, that instantaneous manipulation is impossible as it requires an infinite cost. These findings are illustrated for two experimentally relevant systems—the parametric oscillator and the Landau-Zener model—which reveal that the spectral gap governs the quantum speed limit as well as the cost for realizing the shortcut.

4 September 2019 in Physical Review E
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ASAlan C. Santos
Alan C. Santos
BCBaris Cakmak
Baris Cakmak
SCSteve Campbell
Steve Campbell
NZNikolaj T. Zinner
Nikolaj T. Zinner
With the advent of quantum technologies comes the requirement of building quantum components able to store energy to be used whenever necessary, i.e., quantum batteries. In this paper we exploit an adiabatic protocol to ensure a stable charged state of a three-level quantum battery which allows one to avoid the spontaneous discharging regime. We study the effects of the most relevant sources of noise on the charging process, and, as an experimental proposal, we discuss superconducting transmon qubits. In addition we study the self-discharging of our quantum battery where it is shown that spectrum engineering can be used to delay such phenomena.

1 May 2015 in Physical Review Letters
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SCSteve Campbell
Steve Campbell
GCGabriele De Chiara
Gabriele De Chiara
MPMauro Paternostro
Mauro Paternostro
G. Massimo PalmaG. Massimo Palma
G. Massimo Palma
RFRosario Fazio
Rosario Fazio
We study transitionless quantum driving in an infinite-range many-body system described by the Lipkin-Meshkov-Glick model. Despite the correlation length being always infinite the closing of the gap at the critical point makes the driving Hamiltonian of increasing complexity also in this case. To this aim we develop a hybrid strategy combining a shortcut to adiabaticity and optimal control that allows us to achieve remarkably good performance in suppressing the defect production across the phase transition.

19 August 2020 in Physical Review Letters
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MMMark Mitchison
Mark Mitchison
TFThomas Fogarty
Thomas Fogarty
GGGiacomo Guarnieri
Giacomo Guarnieri
SCSteve Campbell
Steve Campbell
TBThomas Busch
Thomas Busch
JGJohn Goold
John Goold
The precise measurement of low temperatures is a challenging, important, and fundamental task for quantum science. In particular, in situ thermometry is highly desirable for cold atomic systems due to their potential for quantum simulation. Here, we demonstrate that the temperature of a noninteracting Fermi gas can be accurately inferred from the nonequilibrium dynamics of impurities immersed within it, using an interferometric protocol and established experimental methods. Adopting tools from the theory of quantum parameter estimation, we show that our proposed scheme achieves optimal precision in the relevant temperature regime for degenerate Fermi gases in current experiments. We also discover an intriguing trade-off between measurement time and thermometric precision that is controlled by the impurity-gas coupling, with weak coupling leading to the greatest sensitivities. This is explained as a consequence of the slow decoherence associated with the onset of the Anderson orthogonality catastrophe, which dominates the gas dynamics following its local interaction with the immersed impurity.

5 February 2018 in Quantum Science and Technology
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SCSteve Campbell
Steve Campbell
MGMarco G. Genoni
Marco G. Genoni
Sebastian DeffnerSebastian Deffner
Sebastian Deffner
We assess precision thermometry for an arbitrary single quantum system. For a d -dimensional harmonic system we show that the gap sets a single temperature that can be optimally estimated. Furthermore, we establish a simple linear relationship between the gap and this temperature, and show that the precision exhibits a quadratic relationship. We extend our analysis to explore systems with arbitrary spectra, showing that exploiting anharmonicity and degeneracy can greatly enhance the precision of thermometry. Finally, we critically assess the dynamical features of two thermometry protocols for a two level system. By calculating the quantum speed limit we find that, despite the gap fixing a preferred temperature to probe, there is no evidence of this emerging in the dynamical features.