SQuInT 2022 Program
Full Program | Thursday | Friday | Saturday | All Sessions | Posters | Talks
SESSION 9c: Advance in quantum information theory (Mariposa Meeting Room)Chair: (John DeBrota (UNM)) | |
| 3:45 pm - 4:15 pm | Iman Marvian, Duke University Operational Interpretation of Quantum Fisher Information in Quantum Thermodynamics | Abstract. In the framework of quantum thermodynamics preparing a quantum system in a general state requires the consumption of two distinct resources, namely, work and coherence. It has been shown that the work cost of preparing a quantum state is determined by its free energy. Considering a similar setting, here we determine the coherence cost of preparing a general state when there are no restrictions on work consumption. More precisely, the coherence cost is defined as the minimum rate of consumption of systems in a pure coherent state, that is needed to prepare copies of the desired system. We show that the coherence cost of any system is determined by its quantum Fisher information about the time parameter, hence introducing a new operational interpretation of this central quantity of quantum metrology. Our resource-theoretic approach also reveals a previously unnoticed connection between two fundamental properties of quantum Fisher information. |
| 4:15 pm - 4:45 pm | Shawn Geller, University of Colorado Improving quantum state detection with adaptive sequential observations | Abstract. For many quantum systems intended for information processing, one detects the logical state of a qubit by integrating a continuously observed quantity over time. For example, ion and atom qubits are typically measured by driving a cycling transition and counting the number of photons observed from the resulting fluorescence. Instead of recording only the total observed count in a fixed time interval, one can observe the photon arrival times and get a state detection advantage by using the temporal structure in a model such as a hidden Markov model. We study what further advantage may be achieved by applying pulses to adaptively transform the state during the observation. We give a three-state example where adaptively chosen transformations yield a clear advantage, and we compare performances on an ion example, where we see improvements in some regimes. We provide a software package that can be used for exploration of temporally resolved strategies with and without adaptively chosen transformations. |
| 4:45 pm - 5:15 pm | Arjendu Pattanayak, Carleton College Extreme parametric sensitivity in bath-mediated transport due to avoided level crossings: The dissipative quantum Rabi model and others | Abstract. We show that non-equilibrium steady states (NESS) of the quantum Rabi model subject to two dissipative interactions have transport properties that are enhanced as spikes over narrow parameter windows, with a lineshape that depends on details of the model for the system and the dissipation. We also find similar results for related models of quantum transport and light-matter interactions including the Holstein and Dicke Hamiltonians. We show that this phenomenon is due to low-energy avoided crossings in the corresponding closed system. In particular the transport spikes are correlated with spikes in the entanglement entropy of key energy eigenstates of the closed system, a signature of strong mixing and resonance among system degrees of freedom. Further, by comparing the Quantum Rabi model with the Jaynes-Cummings model we show that this phenomenon is related to quantum integrability. The results seem generically relevant and widely applicable, from analyses of chemical reaction dynamics in the condensed phase to the scrambling of information in well-controlled quantum devices. |
| 5:15 pm - 5:45 pm | Luis Pedro Garcia-Pintos, University of Maryland Joint Quantum Institute Reproducing stochastic quantum trajectories and applications to quantum feedback control | Abstract. I show an explicit construction of a Hamiltonian that, given access to a measurement record, reproduces the stochastic trajectories of a continuously monitored quantum system. This provides a tool to engineer quantum control protocols by exploiting measurement feedback. As examples of this, I will show how to emulate the time-reversed dynamics of an open quantum system and a way to prepare a quantum state. Moreover, via suitably chosen feedback Hamiltonians, I show how to mitigate the production of qubit errors with smaller ancilla overheads than traditional quantum error correction techniques if one has access to the environment responsible for the errors. |
| 5:45 pm - 6:15 pm | Mark Webster, University of Sydney 3 Algorithms for non-Clifford operators of CSS codes | Abstract. Finding fault-tolerant non-Clifford logical operators on stabiliser codes is important for realisation of universal quantum computing. This task is particularly challenging for LDPC codes. The XP formalism allows us to better understand the logical operator structure of stabiliser codes, including logical operators at various levels of the Clifford hierarchy. In this talk, I will present 3 algorithms for finding fault-tolerant non-Clifford logical operators of CSS codes |
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SQuInT Chief Organizer
Akimasa Miyake, Associate Professor
amiyake@unm.edu
SQuInT Co-Organizer
Hartmut Haeffner, Associate Professor, UC Berkeley
hhaeffner@berkeley.edu
SQuInT Administrator
Dwight Zier
d29zier@unm.edu
505 277-1850
SQuInT Program Committee
Alberto Alonso, Postdoc, UC Berkeley
Philip Blocher, Postdoc, UNM
Neha Yadav, Postdoc, UC Berkeley
Cunlu Zhou, Postdoc, UNM
SQuInT Founder
Ivan Deutsch, Regents' Professor, CQuIC Director
ideutsch@unm.edu
