QComp! Seminar series on quantum computation

Zoom links are posted on Quantum Center and the QComp! mailing lists before each seminar.
For Zoom link for the upcoming seminar please contact Dr. Judy Kupferman, judithku[at]post.bgu​.ac.il

Thursday, May 27, 15:30-16:30
Cloud-based experiments on many-body dynamics with IBM Quantum devices

Haggai Landa, IBM

Abstract:​
I will present a brief overview of the IBM Quantum roadmap. A central part in this roadmap is devoted to the cloud-based access offered to IBM's quantum devices, and I will focus on the technology of the deployed devices. Together with the devices accessible to the general public and research communities, IBM leads the development of Qiskit, an open-source framework for quantum experiments and simulations. I will present a short review of Qiskit and of the activities of the IBM Research quantum group in Haifa within it, and I will discuss current possibilities for using Qiskit for studying quantum dynamics of open many-body systems.​

Nissim Ofek, Quantum Machines 

Abstract:
In this talk I am going to focus on the control layer of the quantum computing stack. This is the layer that bridges the higher (and more abstract) layers which describe quantum algorithms and an actual (analog) quantum system. As such, it confronts a whole range of constraints coming from both directions. On top of that, we desire that the control layer be agnostic to the specific quantum platform (be it SC qubits, trapped ions, NV center-based systems or anything else). I will elaborate on a notion that the control system is a "subtractive" instrument. Namely, it never enables the full potential of the quantum system. At the end, the "right" control system is a solution of an extremely complex optimization problem, involving many scientific fields. 

​Thursday, Jan.21, 15:30-16:30
Title:  A Hardware-accelerated Qubit Control System for Quantum Information Processing 

Dr. Philip Krantz, Business Development, Quantum Engineering Solutions Keysight Technologies 

Abstract:
In quantum information processing, there has been a rapid increase in the number of qubits connected to each quantum chip/processor. In part, this increase has been enabled through an increased understanding of various noise mechanisms. However, another important factor when building a scaled-up quantum processor is that the classical control system can efficiently control and read out the states of the qubit register. Keysight technologies provides powerful, yet compact solutions, enabling quantum engineers to continuously push the scientific boundaries. In this talk, I will provide a high-level overview of some of the current challenges that quantum engineers face, as well as how Keysight’s HW and SW solutions can help accelerate scientific progress.
​

​​Thursday, Jan.7, 15:​​30-16:30
Title: Quantum noise characterization and verification

Shelly Garion, IBM Quantum - IBM Research Haifa

Abstract:
Quantum computers are at an active stage of research and development that may eventually lead to their practical realization, with potential impact on many fields from chemistry and medication, to financial risk analysis and AI.
One of the major challenges of using quantum computers is noise.
Quantum devices are noisy because the very nature of quantum computing requires creating fragile  superposition states of quantum bits (qubits) and interactions between the qubits.
In this talk, I will review several methods for characterization, verification and validation
of quantum hardware noise, that were implemented as part of Qiskit open-source.
I will focus on Randomized Benchmarking, which is a well-known approach that provides an efficient and reliable experimental estimation of the average error-rate of a set of quantum gates, by running sequences of random gates from the Clifford group.
I will also discuss the Clifford group and the CNOT-Dihedral group, and present our recent work on Randomized Benchmarking of a certain non-Clifford gate. 

References:
[1] https://qiskit.org/textbook/ch-quantum-hardware/randomized-benchmarking.html
[2] Shelly Garion, Naoki Kanazawa, Haggai Landa, David C. McKay, Sarah Sheldon, Andrew W. Cross, Christopher J. Wood,Experimental implementation of non-Clifford interleaved randomized benchmarking with a controlled-S gate, https://arxiv.org/abs/2007.08532
[3] Shelly Garion and Andrew W. Cross, Synthesis of CNOT-Dihedral circuits with optimal number of
two qubit gates, Quantum 4 (369), 2000,  https://arxiv.org/abs/2006.12042
​

Error-Corrected Gates on a Logical Bosonic Q​​​ubit     

Serge Rosenblum, Weizmann Institute of Science, Rehovot, Israel 

Abstract:
In future fault-tolerant quantum computers, errors resulting from noise and decoherence must be detected and corrected in real-time. This is particularly important while applying operations between different elements, which can cause errors to quickly spread throughout the system.

In this talk, I will present an error-corrected construction for operations on a cavity-encoded logical qubit [1,2]. The scheme uses the multilevel structure of a transmon ancilla, along with RF-tunable transmon-cavity interactions, to apply a broad range of operations on a variety of encodings, while protecting the logical qubit against photon loss, as well as ancilla decay and dephasing.  We show that the fidelity of the operations is substantially improved when using the error-corrected implementation compared to the non-corrected one. These results present an important step towards fully fault-tolerant processing of logical bosonic qubits. 

[1] P. Reinhold, SR, et al, Nat. Phys. 16, 822-826 (2020)
[2] W. -L. Ma et al., Phys. Rev. Lett. 125, 110503 (2020) 

Nir Davidson, Weizmann Institute of Science, Rehovot, Israel 

Abstract:
Computational problems may be solved by realizing physics systems that can simulate them. Here we present a new system of up to >1000 coupled lasers that is used to solve difficult computational tasks. The well-controlled dissipative coupling anneals the lasers into a stable phase-locked state with minimal loss,  that can be mapped on different computational minimization problems. We demonstrate this ability for simulating XY spin systems and finding their ground state, for phase retrieval, for imaging through scattering medium and more.