[seminar-cqi] fifi 3

Hi everyone, Following fifi 1 and fifi 2 back in July (which I've heard were great successes -- I was in Greece at the time) we're going to hold "fifi 3" tomorrow on the USI fifth floor, starting at 12:30. Let's keep the format a little free-form but the idea is to hear three talks by Lorenzo, myself, and Carla (at 2 o'clock, remotely from Geneva). Titles and abstracts below. Let's use the jitsi channel, at least initially. It doesn't always work well for Carla so we may switch to another online platform if the connection is poor. https://meet.jit.si/cqi-demon-M6QW9V7YY Hope to see you tomorrow! Will Speaker: Lorenzo Laneve Title: Quantum signal processing over SU(N) Abstract: Quantum signal processing (QSP) is a powerful technique that allows one to implement a polynomial transformation of a unitary matrix given as a controlled black box and using only one qubit, taking advantage of the geometric properties of SU(2). In this ansatz, the degree of the polynomial grows linearly with the number of steps. We show that, by adding more control qubits and black-box access to the powers of two of the unitary operator, we can achieve polynomial transformations of exponentially growing degree. These assumptions also hold in the context of many well-known algorithms that provide super-polynomial advantage over classical algorithms. Speaker: William Schober Title: On the notion of controlled gates Abstract: Controlled gates like CNOT are modeled on their classical counterparts, conditional statements of the form "if x then do y". In a classical computer there is an unambiguous distinction between the control bits x and target bits y. The control bits are read, and the target bits are written to. In a quantum computer this distinction is arbitrary and depends on a local choice of basis. I'll show some examples exchanging control and target, and then introduce a formal definition for a controlled operation. The definition relies on a new(?) mathematical concept I call a partial eigenvector. Speaker: Carla Sophie Rieger Title: QRAM and its Extension Abstract: I will introduce the basic concepts of a Quantum Random Access Memory (QRAM), the writing process of classical data in a QRAM state using the Flip-Flop QRAM Algorithm and an algorithmic QRAM extension procedure that may be used for storing experimental data available as a time-series of initially undefined length.