.. title: PAR Class 20, Thu 2019-03-28
.. slug: class20
.. date: 2019-03-27
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GTC19 videos, part 2
--------------------

#. `GTC 2019 Keynote with NVIDIA CEO Jensen Huang <https://www.youtube.com/watch?v=Z2XlNfCtxwI>`_.

#. `GTC 2019 Automotive Recap <https://www.youtube.com/watch?v=UeZrBV_5PAs>`_.

#. `NVIDIA RTX Comes to Unity to Power Real-Time Ray Tracing <https://www.youtube.com/watch?v=VE1tshplrW4>`_.

#. `NVIDIA Omniverse - The Collaboration Platform for 3D Content Creation <https://www.youtube.com/watch?v=rVsp6o9t5nY>`_.

#. `Quake II RTX - GTC 2019 Demo Walkthrough with NVIDIA CEO Jensen Huang (ultrawide) <https://www.youtube.com/watch?v=vY0W3MkZFs4>`_.



Quantum computing
-----------------

#. https://www.quantum-inspire.com/kbase/introduction-to-quantum-computing/

#. More from

   `Quantum Computing for Computer Scientists 1st Edition <https://www.amazon.com/Quantum-Computing-Computer-Scientists-Yanofsky/dp/0521879965/ref=pd_ybh_a_2?_encoding=UTF8&psc=1&refRID=RJPCXRE73M3GQTTWNE9K>`_ ( recommended in Microsoft talk)

   a. Compare byte with qbyte.

   #. State of byte is 8 bits.

   #. State of qbyte is 256 complex weights.

   #. They all get modified by each operation (aka matrix multiply).

   #. That is the power of quantum computing.

   #. The current limitations are that IBM does only a few qbits and that the operation is noisy.

   #. No cloning:  Cannot copy a qbit, but can move it.

   #. Copied from page 171:  All quantum algorithms work with the following basic framework:

      i. The system will start with the qubits in a particular classical state.
      #. From there the system is put into a superposition of many states.
      #. This is followed by acting on this superposition with several unitary operations.
      #. And finally, a measurement of the qubits.

   #. Ways to look at measurement:

      i. Converts qbit to classical bit.

      #. Is an interaction with the external world.

      #. Information is not lost, but leaks into the external world.

      #. Is an operator represented by a matrix.

      #. that is Hermitian, i.e., it's equal to its complex transpose.

      #. For physical systems, some operators compute the system's momentum, position, or energy.

      #. The matrix's eigenvalues are real.

      #. The result of the operation is one of the eigenvalues.
	 
   #. https://en.m.wikipedia.org/wiki/Bloch_sphere:

      i. The state of a qbit can be represented as a point on or in a sphere of radius 1.

      #. E.g., \|1> is the north pole, \|0> the south pole.

      #. Many operations are rotations.

   #. Common operations (aka gates):

      https://en.wikipedia.org/wiki/Quantum_logic_gate

      i. Hadamard.

	 Creates a superposition.

	 https://cs.stackexchange.com/questions/63859/intuition-behind-the-hadamard-gate

      #. Toffoli, aka CCNOT.

	 Universal for classical boolean functions.

	 (a,b,c) -> (a,b, c xor (a and b))

	 https://en.wikipedia.org/wiki/Toffoli_gate

      #. Fredkin, aka CSWAP.

	 https://en.wikipedia.org/wiki/Fredkin_gate

	 3 inputs.  Swaps last 2 if first is true.

	 sample app:  5 gates make a 3-bit full adder.

#. Algorithms:

   a. Some, but not all, are faster.

   #. Bounded-error quantum polynomial time (BQP)

      i. "is the class of decision problems solvable by a quantum computer in polynomial time, with an error probability of at most 1/3 for all instances" -       https://en.wikipedia.org/wiki/BQP

      #. Includes integer factorization and discrete log.

      #. Relation to NP is unknown (big unsolved problem).

   #. Grover's algorithm:

      i. https://en.wikipedia.org/wiki/Grover%27s_algorithm

      #. Given a black box with N inputs and 1 output.

      #. Exactly one input makes the output 1.
	    
      #. Problem: which one?

      #. Classical solution: Try each input, T=N.

      #. Quantum:  $T=\\sqrt(N)$.

      #. Probabilistic.

      #. Apps: mean, median, reverse a crypto hash, find collisions, generate false blocks.

      #. Can extend to quantum partial search.

      #. Grover's algorithm is optimal.

      #. This suggests that NP is not in BQP .

   #. Shor's algorithm:

      i. Factorize an int.

      #. in BQP.

      #. almost exponentially faster than best classical algorithm.

      #. Largest examples I can find:
	 
         #. 56153 = 233 × 241.

	 #. https://medium.com/@aditya.yadav/rsa-2048-cracked-using-shors-algorithm-on-a-quantum-computer-660cb2297a95	 


#. https://quantumexperience.ng.bluemix.net/qx/tutorial ctd.