Correct answers for the WACQT Summer School test

IVETTE FUENTES

Quantum mechanics and general relativity are incompatible for several reasons including that: the Schrödinger equation has only one time derivative

Entanglement is observer dependent in relativity because: the particle content of a field is different for different observers

JOHN MARTINIS

Q1) What are the eigenstates called for the simultaneous parity bit and phase flip operators X1 X2 and Z1 Z2?
These are the Bell states

Q2) For a spin in a Z-direction B field, the energy difference of the qubit states is 5 GHz.  What is the approximate maximum speed (minimum time) for a pi-pulse, if you are allowed control fields in the x and y directions? 
You can make this gate arbitrarily fast.

Q3) For Q2), but for a control field only in the x-direction, what is the maximum speed?
Maximum speed is about 10 GHz, or about 0.1 ns.

Q4) For a transmon with the 0 to 1 transition frequency of 5 GHz, and a 1 to 2 transition frequency of 4.8 GHz, what is the approximate maximum speed?
Maximum speed is about 200 MHz, or about 5 ns.

PIET SCHMIDT

Which set of parameters gives the best (lowest) statistical undertainty?​






Answer number 1

Which statements concerning clocks and frequency standards are correct?
The statistical uncertainty determines how long we need to average to obtain a certain measured frequency resolution.
And
The systematic uncertainty is given by the uncertainty in the offsets between the measured and unperturbed transition frequency.

What does relativistic geodesy/chronometric leveling depend upon?:
Both Newtonian gravity and relativistic effects

SETH LLOYD

The inventor of quantum computing was: Paul Benioff
The first design for a technologically feasible quantum computer used: electromagnetic resonance

Kitaev's quantum phase estimation algorithm is a digitization of what earlier quantum discovery?: von Neumann pointer variable model

Quantum principal component analysis (qPCA) is based on which quantum subroutine?
All of the above - quantum phase estimation, quantum singular value transform and density matrix exponentiation. 

The future of quantum information processing will be created by: All of us together. (Large companies, small startups, sovereign countries, DARPA)

CHRISTINE SILBERHORN​

How can we scale up photonic quantum systems?
We can use all degrees of freedom (spatial, spectral, temporal) of light to establish large systems and we need to define our system by controlling all of them

What defines the temporal modes of photon pairs produced by parametric downconversion?
The phase matching conditions together with energy conservation of the parametric downconversion process defines the resulting temporal modes. For appropriate phase matchings the shaping of the pump pulses can control the number of occupied TM modes.

SHRUTI PURI

As state is said to have even/odd parity when…​ State is parity-less

Consider the unitary that maps the stabilizer of the cat code to the state of a transmon qubit…
It causes an incorrect measurement outcome

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