Parallelizable Calculation of Observables Values on Analog Quantum Computer ()
1. Introduction: What Is Entanglement in Conventional Approach and in the Geometric Algebra Approach?
In conventional quantum mechanics entanglement means that multiple objects share a single quantum state. Entanglement is the amount by which multiple objects share a quantum state. They remain indeterminate until they are disentangled by a measurement.
The simplest quantum mechanical state, qubit, reads:
,
,
It has just two observable “things” after measurement, say “up” for
and “down” for
, with probabilities
and
. The qubit dimension two is the number of different observable things available after making a measurement on the particle.
In the case of two particles the vector space
is generalized to density matrix defined on tensor product
. The appropriateness of tensor products is that the tensor product itself captures all the ways that basic things can “interact” with each other [1]. Quantum entanglement means that aspects of one particle of an entangled pair depend on aspects of the other particle. Only when the measurement occurs does the quantum state “collapse” make instantaneously collapsing the other particle state.
That’s crucial words: “instantaneously collapsing”. Common wisdom considers that as physically real transformation of the other particle unknown state into the known one.
The scheme suggested in the geometric algebra approach is based on manipulation and transferring of quantum states as operators acting on observables. Wave functions act in that context on static
elements through measurements, creating “particles”, see [2].
When assuming that observables are identified by points on
we get that measurements of any number of observables by arbitrary set of wave functions are simultaneously available, see [1] [3] [4].
This is a geometrically clear and unambiguous explanation of strict connectivity of the results of measurements instead of quite absurd “entanglement” in conventional quantum mechanics.
2. Maxwell Equation in Geometric Algebra
Without charges and currents the Maxwell equation is:
(2.1)
The circular polarized electromagnetic waves are the only type of waves following from the solution of Maxwell equations in free space done in geometric algebra terms. Indeed, let’s take the electromagnetic field in the form:
(2.2)
requiring that it satisfies (2.1).
Element
in (2.2) is a constant element of geometric algebra
and
is unit value bivector of a plane S in three dimensions, generalization of the imaginary unit [3]. The exponent in (2.2) is unit value element of
:
,
Solution of (2.1) should be sum of a vector (electric field e) and bivector (magnetic field
):
For a plane S in three dimensions Maxwell Equation (2.1) has two solutions [5]:
, with
,
, and the triple
is right hand screw oriented, that’s rotation of
to
by π/2 gives movement of right hand screw in the direction of
.
, with
,
, and the triple
is left hand screw oriented, that’s rotation of
to
by
gives movement of left hand screw in the direction of
or, equivalently, movement of right hand screw in the opposite direction,
.
and
, initial values of e and h, are arbitrary mutually orthogonal vectors of equal length, lying on the plane S. Vectors
are normal to that plane. The length of the “wave vectors”
is equal to angular frequency
.
Maxwell Equation (2.1) is a linear one. Then any linear combination of
and
saving the structure of (2.2) will also be a solution.
Let’s write:
(2.3)
Then for arbitrary (real1) scalars
and
:
(2.4)
is solution of (2.1). The item in the second parenthesis is weighted linear combination of two states with the same phase in the same plane but opposite sense of orientation. The states are strictly coupled, entangled if you prefer, because bivector plane should be the same for both, does not matter what happens with that plane.
Arbitrary linear combination (2.4) can be rewritten as:
(2.5)
where
,
The triple of unit value basis orthonormal bivectors
is comprised of the
bivector, dual to the propagation direction vector;
is dual to initial vector of magnetic field;
is dual to initial vector of electric field. The expression (2.5) is linear combination of two geometric algebra states, g-qubits.
Linear combination of the two equally weighted basic solutions of the Maxwell equation
and
,
with
reads:
(2.6)
where
and
. It can be written in standard exponential form
.2
I will call such g-qubits spreons because they spread over the whole three-dimensional space for all values of time and instantly change under Clifford translations over the whole three-dimensional space for all values of time, along with the results of measurement of any observable.3
3. Measurement of Observables by Spreons
Measurement of any observable
(actually Hopf fibration) by a state
in the current formalism is, see, for example, [6]:
2Good to remember that the two basic solutions
and
differ only by the sign of
, which is caused by orientation of
that in its turn defines if the triple
is right-hand screw or left-hand screw oriented.
In the case of spreon (2.6):
,
,
,
,
and we get a
element spreading through the three-dimensional space for all values of the time parameter t. It is
element spreading through the three-dimensional space for all values of time parameter t:
(3.1)
Geometrically, that means that the measured observable is rotated by
in the
plane, such that the
component becomes orthogonal to plane
and remains unchanged. Two other components became orthogonal to
and
and continue rotating in
with angular velocity
. The factor
defines the dependency of that transformed values through all points of the three-dimensional space.
In the current scheme any test observable can be placed anywhere into continuum of the
dependent values of the spreon state. The above formula (3.1) gives the result of measurements simultaneously at all points
.
Assume we have two observables,
and
. Write them in exponential form:
where
,
,
,
,
where
,
,
,
,
.
The observable
can be written as:
,
and then its measurement by any g-qubit
reads:
(3.2)
that is, up to the factor
, the result of measurement of
, multiplied by the result of measurement of
.
4. Simultaneous Measurement of Observables by Spreons
Now let us use the result (3.2) of not made measurement in the case of state (2.6).
One remaining unspecified item is
. Its
expression follows, see e.g. [4], from known formulas. If
where
in some bivector basis
, with multiplication rules
,
,
, then the scalar part of
is:
,
and bivector part:
Now it remains to apply (3.1) with
The result of measuring of
is, due to (3.1),
And the result of measuring of
is
Finally, the result of not made measuring of
is received from the result of measuring of
as:
,
where the product of two subalgebra
elements is calculated by known formula (see, [4]):
5. Conclusion
The geometric algebra lift of conventional quantum mechanics qubits is the game-changing quantum leap forward. The approach brings into reality a kind of physical field spreading through the whole three-dimensional space and values of the time parameter. All measured observable values are simultaneously available all together, not through looking one by one. In this way the new type of quantum computer appeared to be a kind of analog computer keeping and instantly processing information by and on sets of objects possessing an infinite number of degrees of freedom.
NOTES
1Remember, in the current theory scalars are real ones. “Complex” scalars have no sense.
3The two received solutions are similar in their form to the Majorana operators, though with a bivector instead of formal imaginary unit. Thus, not surprising that the following computational scheme represents more general software simulation which gets around the problem of physical implementation of Majorana fermions.